Clean up tests a bit

[TobiX]

• Remove useless classes
• Move more common code into PyTest fixtures
• Split version checks into a new file

[codecov]

Codecov Report

❌ Patch coverage is 98.74214% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 89.39%. Comparing base (b0c512b) to head (6786337).

Files with missing lines	Patch %	Lines
tests/test_modules.py	93.65%	4 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #391      +/-   ##
==========================================
+ Coverage   89.32%   89.39%   +0.06%     
==========================================
  Files          97       98       +1     
  Lines        7084     7041      -43     
  Branches     1152     1148       -4     
==========================================
- Hits         6328     6294      -34     
+ Misses        756      747       -9     

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