Remove deprecated code

I checked drupal 9 compatibilities for this module in drupal-check I found the following deprecated methods.

60/60 [▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓] 100%

------ --------------------------------------------------------------------------------------
Line src/Controller/TetherStatsTrackController.php
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190 Call to deprecated method checkPlain() of class Drupal\Component\Utility\SafeMarkup:
Will be removed before Drupal 9.0.0. Rely on Twig's
auto-escaping feature, or use the @link theme_render #plain_text @endlink
key when constructing a render array that contains plain text in order to
use the renderer's auto-escaping feature. If neither of these are
possible, \Drupal\Component\Utility\Html::escape() can be used in places
where explicit escaping is needed.
190 Call to method checkPlain() of deprecated class Drupal\Component\Utility\SafeMarkup:
Will be removed before Drupal 9.0.0. Use the appropriate
------ --------------------------------------------------------------------------------------

------ ------------------------------------------------------------------
Line src/Form/TetherStatsElementFinderForm.php
------ ------------------------------------------------------------------
262 Call to deprecated function entity_load():
in Drupal 8.0.x, will be removed before Drupal 9.0.0. Use the
entity type storage's load() method.
419 Call to deprecated function db_or():
as of Drupal 8.0.x, will be removed in Drupal 9.0.0. Create
a \Drupal\Core\Database\Query\Condition object, specifying an OR
conjunction: new Condition('OR');
428 Call to deprecated function db_or():
as of Drupal 8.0.x, will be removed in Drupal 9.0.0. Create
a \Drupal\Core\Database\Query\Condition object, specifying an OR
conjunction: new Condition('OR');
------ ------------------------------------------------------------------

------ ------------------------------------------------------------------
Line src/Plugin/tether_stats/Chart/TetherStatsChartRendererGoogle.php
------ ------------------------------------------------------------------
246 Call to deprecated function format_date():
in Drupal 8.0.0, will be removed before Drupal 9.0.0.
Use \Drupal::service('date.formatter')->format().
250 Call to deprecated function format_date():
in Drupal 8.0.0, will be removed before Drupal 9.0.0.
Use \Drupal::service('date.formatter')->format().
254 Call to deprecated function format_date():
in Drupal 8.0.0, will be removed before Drupal 9.0.0.
Use \Drupal::service('date.formatter')->format().
259 Call to deprecated function format_date():
in Drupal 8.0.0, will be removed before Drupal 9.0.0.
Use \Drupal::service('date.formatter')->format().
------ ------------------------------------------------------------------

------ ----------------------------------------------------------------------------------
Line src/Tests/TetherStatsAnalyticsStorageTest.php
------ ----------------------------------------------------------------------------------
162 Call to deprecated method format() of class Drupal\Component\Utility\SafeMarkup:
in Drupal 8.0.0, will be removed before Drupal 9.0.0.
Use \Drupal\Component\Render\FormattableMarkup.
162 Call to method format() of deprecated class Drupal\Component\Utility\SafeMarkup:
Will be removed before Drupal 9.0.0. Use the appropriate
182 Call to deprecated method format() of class Drupal\Component\Utility\SafeMarkup:
in Drupal 8.0.0, will be removed before Drupal 9.0.0.
Use \Drupal\Component\Render\FormattableMarkup.
182 Call to method format() of deprecated class Drupal\Component\Utility\SafeMarkup:
Will be removed before Drupal 9.0.0. Use the appropriate
226 Call to deprecated method format() of class Drupal\Component\Utility\SafeMarkup:
in Drupal 8.0.0, will be removed before Drupal 9.0.0.
Use \Drupal\Component\Render\FormattableMarkup.
226 Call to method format() of deprecated class Drupal\Component\Utility\SafeMarkup:
Will be removed before Drupal 9.0.0. Use the appropriate
246 Call to deprecated method format() of class Drupal\Component\Utility\SafeMarkup:
in Drupal 8.0.0, will be removed before Drupal 9.0.0.
Use \Drupal\Component\Render\FormattableMarkup.
246 Call to method format() of deprecated class Drupal\Component\Utility\SafeMarkup:
Will be removed before Drupal 9.0.0. Use the appropriate
358 Call to deprecated method url() of class Drupal\Core\Entity\EntityInterface:
in Drupal 8.0.0, intended to be removed in Drupal 9.0.0
Please use toUrl() instead.
------ ----------------------------------------------------------------------------------

------ ----------------------------------------------------------------------------------
Line src/Tests/TetherStatsIdentitySetTest.php
------ ----------------------------------------------------------------------------------
55 Call to deprecated method format() of class Drupal\Component\Utility\SafeMarkup:
in Drupal 8.0.0, will be removed before Drupal 9.0.0.
Use \Drupal\Component\Render\FormattableMarkup.
55 Call to method format() of deprecated class Drupal\Component\Utility\SafeMarkup:
Will be removed before Drupal 9.0.0. Use the appropriate
68 Call to deprecated method format() of class Drupal\Component\Utility\SafeMarkup:
in Drupal 8.0.0, will be removed before Drupal 9.0.0.
Use \Drupal\Component\Render\FormattableMarkup.
68 Call to method format() of deprecated class Drupal\Component\Utility\SafeMarkup:
Will be removed before Drupal 9.0.0. Use the appropriate
82 Call to deprecated method url() of class Drupal\Core\Entity\EntityInterface:
in Drupal 8.0.0, intended to be removed in Drupal 9.0.0
Please use toUrl() instead.
97 Call to deprecated method url() of class Drupal\Core\Entity\EntityInterface:
in Drupal 8.0.0, intended to be removed in Drupal 9.0.0
Please use toUrl() instead.
106 Call to deprecated method format() of class Drupal\Component\Utility\SafeMarkup:
in Drupal 8.0.0, will be removed before Drupal 9.0.0.
Use \Drupal\Component\Render\FormattableMarkup.
106 Call to method format() of deprecated class Drupal\Component\Utility\SafeMarkup:
Will be removed before Drupal 9.0.0. Use the appropriate
148 Call to deprecated method format() of class Drupal\Component\Utility\SafeMarkup:
in Drupal 8.0.0, will be removed before Drupal 9.0.0.
Use \Drupal\Component\Render\FormattableMarkup.
148 Call to method format() of deprecated class Drupal\Component\Utility\SafeMarkup:
Will be removed before Drupal 9.0.0. Use the appropriate
154 Call to deprecated method url() of class Drupal\Core\Entity\EntityInterface:
in Drupal 8.0.0, intended to be removed in Drupal 9.0.0
Please use toUrl() instead.
163 Call to deprecated method format() of class Drupal\Component\Utility\SafeMarkup:
in Drupal 8.0.0, will be removed before Drupal 9.0.0.
Use \Drupal\Component\Render\FormattableMarkup.
163 Call to method format() of deprecated class Drupal\Component\Utility\SafeMarkup:
Will be removed before Drupal 9.0.0. Use the appropriate
178 Call to deprecated method format() of class Drupal\Component\Utility\SafeMarkup:
in Drupal 8.0.0, will be removed before Drupal 9.0.0.
Use \Drupal\Component\Render\FormattableMarkup.
178 Call to method format() of deprecated class Drupal\Component\Utility\SafeMarkup:
Will be removed before Drupal 9.0.0. Use the appropriate
228 Call to deprecated method format() of class Drupal\Component\Utility\SafeMarkup:
in Drupal 8.0.0, will be removed before Drupal 9.0.0.
Use \Drupal\Component\Render\FormattableMarkup.
228 Call to method format() of deprecated class Drupal\Component\Utility\SafeMarkup:
Will be removed before Drupal 9.0.0. Use the appropriate
236 Call to deprecated method url() of class Drupal\Core\Entity\EntityInterface:
in Drupal 8.0.0, intended to be removed in Drupal 9.0.0
Please use toUrl() instead.
248 Call to deprecated method format() of class Drupal\Component\Utility\SafeMarkup:
in Drupal 8.0.0, will be removed before Drupal 9.0.0.
Use \Drupal\Component\Render\FormattableMarkup.
248 Call to method format() of deprecated class Drupal\Component\Utility\SafeMarkup:
Will be removed before Drupal 9.0.0. Use the appropriate
261 Call to deprecated method format() of class Drupal\Component\Utility\SafeMarkup:
in Drupal 8.0.0, will be removed before Drupal 9.0.0.
Use \Drupal\Component\Render\FormattableMarkup.
261 Call to method format() of deprecated class Drupal\Component\Utility\SafeMarkup:
Will be removed before Drupal 9.0.0. Use the appropriate
------ ----------------------------------------------------------------------------------

------ ----------------------------------------------------------------------------------
Line src/Tests/TetherStatsStorageTest.php
------ ----------------------------------------------------------------------------------
28 Call to deprecated method format() of class Drupal\Component\Utility\SafeMarkup:
in Drupal 8.0.0, will be removed before Drupal 9.0.0.
Use \Drupal\Component\Render\FormattableMarkup.
28 Call to method format() of deprecated class Drupal\Component\Utility\SafeMarkup:
Will be removed before Drupal 9.0.0. Use the appropriate
39 Call to deprecated method format() of class Drupal\Component\Utility\SafeMarkup:
in Drupal 8.0.0, will be removed before Drupal 9.0.0.
Use \Drupal\Component\Render\FormattableMarkup.
39 Call to method format() of deprecated class Drupal\Component\Utility\SafeMarkup:
Will be removed before Drupal 9.0.0. Use the appropriate
50 Call to deprecated method format() of class Drupal\Component\Utility\SafeMarkup:
in Drupal 8.0.0, will be removed before Drupal 9.0.0.
Use \Drupal\Component\Render\FormattableMarkup.
50 Call to method format() of deprecated class Drupal\Component\Utility\SafeMarkup:
Will be removed before Drupal 9.0.0. Use the appropriate
103 Call to deprecated method format() of class Drupal\Component\Utility\SafeMarkup:
in Drupal 8.0.0, will be removed before Drupal 9.0.0.
Use \Drupal\Component\Render\FormattableMarkup.
103 Call to method format() of deprecated class Drupal\Component\Utility\SafeMarkup:
Will be removed before Drupal 9.0.0. Use the appropriate
------ ----------------------------------------------------------------------------------

------ ------------------------------------------------------------------------------
Line src/Tests/TetherStatsTestBase.php
------ ------------------------------------------------------------------------------
139 Call to deprecated method url() of class Drupal\Core\Entity\EntityInterface:
in Drupal 8.0.0, intended to be removed in Drupal 9.0.0
Please use toUrl() instead.
------ ------------------------------------------------------------------------------

------ --------------------------------------------------------------------------------------
Line src/TetherStatsDerivativeListBuilder.php
------ --------------------------------------------------------------------------------------
43 Call to deprecated method checkPlain() of class Drupal\Component\Utility\SafeMarkup:
Will be removed before Drupal 9.0.0. Rely on Twig's
auto-escaping feature, or use the @link theme_render #plain_text @endlink
key when constructing a render array that contains plain text in order to
use the renderer's auto-escaping feature. If neither of these are
possible, \Drupal\Component\Utility\Html::escape() can be used in places
where explicit escaping is needed.
43 Call to method checkPlain() of deprecated class Drupal\Component\Utility\SafeMarkup:
Will be removed before Drupal 9.0.0. Use the appropriate
------ --------------------------------------------------------------------------------------

------ ---------------------------------------------------------------
Line src/TetherStatsIdentitySet.php
------ ---------------------------------------------------------------
228 Call to deprecated function entity_load():
in Drupal 8.0.x, will be removed before Drupal 9.0.0. Use the
entity type storage's load() method.
------ ---------------------------------------------------------------

------ --------------------------------------------------------------------------------------
Line src/TetherStatsManager.php
------ --------------------------------------------------------------------------------------
262 Call to deprecated method checkPlain() of class Drupal\Component\Utility\SafeMarkup:
Will be removed before Drupal 9.0.0. Rely on Twig's
auto-escaping feature, or use the @link theme_render #plain_text @endlink
key when constructing a render array that contains plain text in order to
use the renderer's auto-escaping feature. If neither of these are
possible, \Drupal\Component\Utility\Html::escape() can be used in places
where explicit escaping is needed.
262 Call to method checkPlain() of deprecated class Drupal\Component\Utility\SafeMarkup:
Will be removed before Drupal 9.0.0. Use the appropriate
268 Call to deprecated method checkPlain() of class Drupal\Component\Utility\SafeMarkup:
Will be removed before Drupal 9.0.0. Rely on Twig's
auto-escaping feature, or use the @link theme_render #plain_text @endlink
key when constructing a render array that contains plain text in order to
use the renderer's auto-escaping feature. If neither of these are
possible, \Drupal\Component\Utility\Html::escape() can be used in places
where explicit escaping is needed.
268 Call to method checkPlain() of deprecated class Drupal\Component\Utility\SafeMarkup:
Will be removed before Drupal 9.0.0. Use the appropriate
275 Call to deprecated method checkPlain() of class Drupal\Component\Utility\SafeMarkup:
Will be removed before Drupal 9.0.0. Rely on Twig's
auto-escaping feature, or use the @link theme_render #plain_text @endlink
key when constructing a render array that contains plain text in order to
use the renderer's auto-escaping feature. If neither of these are
possible, \Drupal\Component\Utility\Html::escape() can be used in places
where explicit escaping is needed.
275 Call to method checkPlain() of deprecated class Drupal\Component\Utility\SafeMarkup:
Will be removed before Drupal 9.0.0. Use the appropriate
281 Call to deprecated method checkPlain() of class Drupal\Component\Utility\SafeMarkup:
Will be removed before Drupal 9.0.0. Rely on Twig's
auto-escaping feature, or use the @link theme_render #plain_text @endlink
key when constructing a render array that contains plain text in order to
use the renderer's auto-escaping feature. If neither of these are
possible, \Drupal\Component\Utility\Html::escape() can be used in places
where explicit escaping is needed.
281 Call to method checkPlain() of deprecated class Drupal\Component\Utility\SafeMarkup:
Will be removed before Drupal 9.0.0. Use the appropriate
287 Call to deprecated method checkPlain() of class Drupal\Component\Utility\SafeMarkup:
Will be removed before Drupal 9.0.0. Rely on Twig's
auto-escaping feature, or use the @link theme_render #plain_text @endlink
key when constructing a render array that contains plain text in order to
use the renderer's auto-escaping feature. If neither of these are
possible, \Drupal\Component\Utility\Html::escape() can be used in places
where explicit escaping is needed.
287 Call to method checkPlain() of deprecated class Drupal\Component\Utility\SafeMarkup:
Will be removed before Drupal 9.0.0. Use the appropriate
288 Call to deprecated method checkPlain() of class Drupal\Component\Utility\SafeMarkup:
Will be removed before Drupal 9.0.0. Rely on Twig's
auto-escaping feature, or use the @link theme_render #plain_text @endlink
key when constructing a render array that contains plain text in order to
use the renderer's auto-escaping feature. If neither of these are
possible, \Drupal\Component\Utility\Html::escape() can be used in places
where explicit escaping is needed.
288 Call to method checkPlain() of deprecated class Drupal\Component\Utility\SafeMarkup:
Will be removed before Drupal 9.0.0. Use the appropriate
------ --------------------------------------------------------------------------------------

[ERROR] Found 64 errors