Omit py_modules in setup

[EliahKagan]

This removes the py_modules keyword argument in the call to setup, and further shortens/simplifies setup.py by removing the newly unused build_py_modules function.

The packages keyword argument already covers this, because we have no loose modules that are included in the distribution, and the call to find_packages:

• Omits everything in test/ because it is directed to do so in the call.
• Omits the gitdb/ directory (currently existing as a git submodule, not to be confused with Python submodules). This is because the ext/ directory that contains it does not itself directly contain an __init__.py file, so ext/ is not a traditional package, yet ext/ is contained and found inside the directory git/ that is a traditional package, so the ext/ directory is not a namespace package either.
• Includes all other modules, recursively, because they are all in a recursive traditional package structure under git/ that find_packages recognizes.

To verify that this includes the same files in the built wheel and sdist distributions, I have listed the contents of the wheel with unzip -l and the sdist .tar.gz file with tar tf both before and after this change, verifying they list all the same entries before and after.

[Byron]

Thanks a lot! It's amazing to see that, at least by now, the manual package collection isn't at all necessary anymore and I wonder why it ever was. Oh well 😅.