bdist_pyinstaller doesn't support namespace package

[jaustinpage]

If a package is a namespace package, bdist_pyinstaller raises a TypeError.

Traceback (most recent call last):
  File "/repo/setup.py", line 13, in <module>
    setup(use_scm_version={"version_scheme": "no-guess-dev"})
  File "/repo/.venv/lib/python3.9/site-packages/setuptools/__init__.py", line 153, in setup
    return distutils.core.setup(**attrs)
  File "/app/vbuild/RHEL7-x86_64/python/3.9.5/lib/python3.9/distutils/core.py", line 148, in setup
    dist.run_commands()
  File "/app/vbuild/RHEL7-x86_64/python/3.9.5/lib/python3.9/distutils/dist.py", line 966, in run_commands
    self.run_command(cmd)
  File "/app/vbuild/RHEL7-x86_64/python/3.9.5/lib/python3.9/distutils/dist.py", line 985, in run_command
    cmd_obj.run()
  File "/repo/.venv/lib/python3.9/site-packages/bdist_pyinstaller/bdist_pyinstaller.py", line 394, in run
    PACKAGE__ROOT = os.path.join(os.path.dirname(_package_.__file__))
  File "/app/vbuild/RHEL7-x86_64/python/3.9.5/lib/python3.9/posixpath.py", line 152, in dirname
    p = os.fspath(p)
TypeError: expected str, bytes or os.PathLike object, not NoneType

Per Pep420: https://peps.python.org/pep-0420/#differences-between-namespace-packages-and-regular-packages , namespace packages are defined as packages that have a __path__ but do not have a __file__.

[wherka-ama]

@jaustinpage : thank you for raising the issue. Any chance of providing a quick reproducer please? We could use that to enrich the unit tests once the fix is done.