PHP 8.2 Compatibility Fixes

Please document the problem that this MR is attempting to solve.

For example, the issue title is "PHP 8.2" but the MR is "PHP 8.1". It is unclear what this is supposed to do.

📌 Move from arthurkushman/querypath to GravityPDF/querypath Needs review has to get in before we can make progress on this.

📌 Move from arthurkushman/querypath to GravityPDF/querypath Needs review is in so setting to "needs review".

The php8.2 branch does two things: adds additional composer/phpstan/phpunit tests for the highest version of PHP supported by core (currently 8.3, will be updated automatically in the future) and then fixes the single PHP 8.2 deprecation (dynamic declaration of property).

By automatically testing against the highest supported version of PHP, it will be easy to catch similar issues with the automated tests going forward.

I removed the usage of the class property $feedType in the test FeedTypeEditFormTest, because I didn't see really the benefit of using a class property here. In some tests this is used to create a feed type that is then use in multiple tests. But here we only have one test.

I also updated the GitLab CI file using the latest template of https://git.drupalcode.org/project/gitlab_templates/-/blob/main/gitlab-c....

I merged the code!

Automatically closed - issue fixed for 2 weeks with no activity.