Moved the metadata into machine-readable setup.cfg.

[KOLANICH]

Version is now fetched from git tags automatically.

[codecov]

Codecov Report

Merging #2448 (faaab17) into master (e930d11) will decrease coverage by 5.78%.
The diff coverage is n/a.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2448      +/-   ##
==========================================
- Coverage   98.96%   93.17%   -5.79%     
==========================================
  Files         117      116       -1     
  Lines       16119    16118       -1     
  Branches     3122     3122              
==========================================
- Hits        15952    15018     -934     
- Misses        116     1011     +895     
- Partials       51       89      +38     

Impacted Files	Coverage Δ
trio/_windows_pipes.py	0.00% <0.00%> (-100.00%)	⬇️
trio/_wait_for_object.py	0.00% <0.00%> (-100.00%)	⬇️
trio/_core/_windows_cffi.py	0.00% <0.00%> (-100.00%)	⬇️
trio/_subprocess_platform/windows.py	0.00% <0.00%> (-100.00%)	⬇️
...tests/test_multierror_scripts/apport_excepthook.py	0.00% <0.00%> (-100.00%)	⬇️
trio/_core/_io_windows.py	0.00% <0.00%> (-98.77%)	⬇️
trio/tests/test_wait_for_object.py	10.37% <0.00%> (-89.63%)	⬇️
trio/_core/tests/test_windows.py	17.82% <0.00%> (-82.18%)	⬇️
trio/tests/test_windows_pipes.py	24.67% <0.00%> (-75.33%)	⬇️
trio/_subprocess_platform/__init__.py	62.85% <0.00%> (-37.15%)	⬇️
... and 26 more

[pquentin]

Closing in favor of #2449 because if we're going to do that it will be with pyproject.toml.