feat: support setuptools dynamic dependencies

[mkniewallner]

Closes #421.
Closes #724.

PR Checklist

• A description of the changes is added to the description of this PR.
• If there is a related issue, make sure it is linked to this PR.
• If you've fixed a bug or added code that should be tested, add tests!
• If you've added or modified a feature, documentation in docs is updated

Description of changes

Continuing the work made in #724.

Specification for setuptools dynamic dependecnies: https://setuptools.pypa.io/en/stable/userguide/pyproject_config.html#dynamic-metadata.

In comparison to the initial implementation, this PR moves the logic into PEP621DependencyGetter, since dynamic dependencies in setuptools are only supported when using PEP 621 metadata definition. This also makes it possible to handle cases where only dependencies or optional dependencies are defined dynamically, since it's a valid use case.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 92.5%. Comparing base (fca9448) to head (1ff9347).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##            main    #894     +/-   ##
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+ Coverage   92.4%   92.5%   +0.1%     
=======================================
  Files         37      37             
  Lines        994    1011     +17     
  Branches      96      99      +3     
=======================================
+ Hits         919     936     +17     
  Misses        60      60             
  Partials      15      15             

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[fofoni]

Thanks for this!