docs: run tests in CI

[MaximilianSoerenPollak]

Currently we are not requiring that all tests pass to pass the CI.
I'm guessing this was disabled due to the warnings/checks we had in the Build.
Once these are dealt with I think we should enable tests as a part of the CI, in order to ensure new PR's don't break old functionality without us knowing.

[AlexanderLanin]

Do we have an issue to actually fix the tests? Sounds like useless paperwork, but we do need at the moment for milestone planning.

Proposal: extend this issue to also fixing the tests.

[AlexanderLanin]

Updated proposal: The best approach to fixing the tests is fixing pyright. And fixing pyright without fixing the tests doesn't make sense. Move "fix all tests" to #531 ?!

[AlexanderLanin]

Task: fix remaining tests (currently only docs)
Blocked by #531 as it makes sense to fix pyright issues first