Add meta-test to ensure all .py files follow PEP 563

[haakonvt]

Description

Add meta-test to ensure all .py files follow PEP 563 – Postponed Evaluation of Annotations

• Also removed a "dated" module docstring in cognite/client/utils/_auxiliary.py

Needed for #1314 🤓

Checklist:

• Tests added/updated.
• Documentation updated. Documentation is generated from docstrings - these must be updated according to your change.
  If a new method has been added it should be referenced in cognite.rst in order to generate docs based on its docstring.
• Changelog updated in CHANGELOG.md.
• Version bumped. If triggering a new release is desired, bump the version number in _version.py and pyproject.toml per semantic versioning.

[codecov]

Codecov Report

Merging #1318 (2b719a9) into master (d45b7e8) will decrease coverage by 0.02%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #1318      +/-   ##
==========================================
- Coverage   90.68%   90.67%   -0.02%     
==========================================
  Files         106      108       +2     
  Lines       12583    12589       +6     
==========================================
+ Hits        11411    11415       +4     
- Misses       1172     1174       +2     

Files Changed	Coverage Δ
cognite/client/utils/_auxiliary.py	90.14% <ø> (ø)
cognite/client/_api/__init__.py	100.00% <100.00%> (ø)
...ient/_api/data_modeling/_data_modeling_executor.py	81.25% <100.00%> (+1.25%)	⬆️
cognite/client/data_classes/__init__.py	100.00% <100.00%> (ø)
...e/client/data_classes/annotation_types/__init__.py	100.00% <100.00%> (ø)
...nite/client/data_classes/data_modeling/__init__.py	100.00% <100.00%> (ø)
cognite/client/utils/_graph.py	96.29% <100.00%> (+0.14%)	⬆️

... and 1 file with indirect coverage changes