Remove python_minimal interface

[bryanwweber]

Changes proposed in this pull request

• Remove the python_minimal interface
• Refactor the configuration for the Python/Cython interface to simplify
• Use version specifiers in the setup.cfg.in file. Requires the packaging package; pkg_resources is deprecated anyways.

If applicable, fill in the issue number this pull request is fixing

Closes https://github.com/Cantera/enhancements/issues/208

If applicable, provide an example illustrating new features this pull request is introducing

Checklist

• [x] The pull request includes a clear description of this code change
• [x] Commit messages have short titles and reference relevant issues
• [x] Build passes (scons build & scons test) and unit tests address code coverage
• [x] Style & formatting of contributed code follows contributing guidelines
• [x] The pull request is ready for review

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 73.04%. Comparing base (a1ee588) to head (8832890).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #1745 +/- ## ======================================= Coverage 73.04% 73.04% ======================================= Files 381 381 Lines 54164 54164 Branches 9240 9240 ======================================= Hits 39562 39562 Misses 11633 11633 Partials 2969 2969 ```

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.

[bryanwweber]

Thanks @ischoegl! I noticed some potential Name/Key errors when I was doing a last look, so I pushed a fix in 8832890e3059601e54aeb2a70b5ebf141e18400c