Fix Python build

[mpkorstanje]

🤔 What's changed?

Allow test dependencies to be set by setup.cfg.

See the documentation at: https://packaging.python.org/en/latest/guides/writing-pyproject-toml/#static-vs-dynamic-metadata

⚡️ What's your motivation?

Build broke with:

 × Getting requirements to build wheel did not run successfully.
  │ exit code: 1
  ╰─> [51 lines of output]
      /tmp/pip-build-env-25mh8v9e/overlay/lib/python3.8/site-packages/setuptools/config/_apply_pyprojecttoml.py:75: _MissingDynamic: `optional-dependencies` defined outside of `pyproject.toml` is ignored.
      !!
      
              ********************************************************************************
              The following seems to be defined outside of `pyproject.toml`:
      
              `optional-dependencies = {'test': ['tox']}`
      
              According to the spec (see the link below), however, setuptools CANNOT
              consider this value unless `optional-dependencies` is listed as `dynamic`.
      
              https://packaging.python.org/en/latest/specifications/declaring-project-metadata/
      
              To prevent this problem, you can list `optional-dependencies` under `dynamic` or alternatively
              remove the `[project]` table from your file and rely entirely on other means of
              configuration.
              ********************************************************************************
      
      !!

♻️ Anything particular you want feedback on?

@elchupanebrej you originally added the build in #209. Does this make sense? Are there more elegant ways to resolve this? Feel free to comment or send a PR, even if this was already merged.

📋 Checklist:

• I agree to respect and uphold the Cucumber Community Code of Conduct
• I've changed the behaviour of the code
  • I have added/updated tests to cover my changes.
• My change requires a change to the documentation.
  • I have updated the documentation accordingly.
• Users should know about my change
  • I have added an entry to the "Unreleased" section of the CHANGELOG, linking to this pull request.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (c7a36c3) 91.17% compared to head (b171dc8) 91.17%.
Report is 4 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #240   +/-   ##
=======================================
  Coverage   91.17%   91.17%           
=======================================
  Files           2        2           
  Lines          34       34           
=======================================
  Hits           31       31           
  Misses          3        3           

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