Py-md-doc

- Fixed: Can't upload to PyPi due to bad version classifiers.

- Added `BaseDoc` abstract class. `ClassInteritance` and `PyMdDoc` are now subclasses of `BaseDoc`.
- All `ClassInheritance` classes are no longer static.
- `ClassInheritance` can be constructed with an optional `metadata_path` parameter, which does the same thing as in `PyMdDoc`.
- Extended supported Python versions up to 3.12

- Fixed: Default class variable values that include `"\n"` are parsed as line breaks

- Fixed: Bad regex could cause class inheritance documentation to include too much text

- Fixed: The order of inherited class variables is non-deterministic

- Fixed: Occasional missing ` Function` header
- Fixed: Occasional missing ` Class Variables` header
- Fixed: Occasional incorrect constructor info