Replace versioneer with hard-coded version

[Stoops-ML]

Version defined in src/czml3/version.txt

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 99.25%. Comparing base (1a7dd32) to head (02e2b61).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #141      +/-   ##
==========================================
- Coverage   99.26%   99.25%   -0.01%     
==========================================
  Files          13       12       -1     
  Lines         811      806       -5     
==========================================
- Hits          805      800       -5     
  Misses          6        6              

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[astrojuanlu]

May I suggest using this approach https://setuptools.pypa.io/en/latest/userguide/pyproject_config.html#dynamic-metadata ?

Hence migrating to pyproject.toml but keeping setuptools, adding a __version__ attribute to czml3/__init__.py, and using that like

[tool.setuptools.dynamic]
version = {attr = "czml3.__version__"}