Fix D10 deprecations

Problem/Motivation

Deprecations are by design a moving target, drupal core keeps adding new deprecations as it develops, not having any deprecations means you can only support the most recent (possibly still in-development) core branch. Also, your tests keep breaking on their own. Even right now, there might already be deprecations when testing on D10 for D11.

Therefore, I recommend to not have tests fail on deprecations. Instead, flip the switch/add drupalci.yml only temporarily as a patch when adding compatibility for a new major core version or just run test against the new version (enabling deprecations is helpful to catch some non-obvious deprecations as you often get more helpful errors and can do that if your test dependencies aren't compatible yet).

Steps to reproduce

Proposed resolution

Remove drupalci.yml. Alternatively, switch the suppress deprecations flag if using an optimized configuration, but simplenews doesn't have that it seems.

Remaining tasks

User interface changes

API changes

Data model changes