Omit py_modules in setup

This removes the py_modules keyword argument in the call to setup,
and further shortens/simplifies setup.py by removing the now-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), because the ext/
  directory that contains it does not itself directly contain an
  __init__.py file, so it 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.

setup.py

@@ -4,7 +4,6 @@
 from setuptools import setup, find_packages
 from setuptools.command.build_py import build_py as _build_py
 from setuptools.command.sdist import sdist as _sdist
-import fnmatch
 import os
 import sys
 
@@ -62,24 +61,6 @@ def _stamp_version(filename: str) -> None:
         print("WARNING: Couldn't find version line in file %s" % filename, file=sys.stderr)
 
 
-def build_py_modules(basedir: str, excludes: Sequence = ()) -> Sequence:
-    # create list of py_modules from tree
-    res = set()
-    _prefix = os.path.basename(basedir)
-    for root, _, files in os.walk(basedir):
-        for f in files:
-            _f, _ext = os.path.splitext(f)
-            if _ext not in [".py"]:
-                continue
-            _f = os.path.join(root, _f)
-            _f = os.path.relpath(_f, basedir)
-            _f = "{}.{}".format(_prefix, _f.replace(os.sep, "."))
-            if any(fnmatch.fnmatch(_f, x) for x in excludes):
-                continue
-            res.add(_f)
-    return list(res)
-
-
 setup(
     name="GitPython",
     cmdclass={"build_py": build_py, "sdist": sdist},
@@ -91,7 +72,6 @@ def build_py_modules(basedir: str, excludes: Sequence = ()) -> Sequence:
     url="https://github.com/gitpython-developers/GitPython",
     packages=find_packages(exclude=["test", "test.*"]),
     include_package_data=True,
-    py_modules=build_py_modules("./git", excludes=["git.ext.*"]),
     package_dir={"git": "git"},
     python_requires=">=3.7",
     install_requires=requirements,