text: Title: pdoc does not seem to play nicely with GitPython when in a package
  Body: #### Problem Description
  
  pdoc is unable to import package that uses GitPython.
  
  We've noticed this issue in a large application, and I have created a minimal example that has been able to reproduce the issue here: https://github.com/cquick01/pdoc-test
  
  Our larger application runs fine when running normally, and that other `pdoc3` tool has no issues. So it is definitely something that `pdoc` is doing differently than the rest. When commenting out references to GitPython in our larger application, `pdoc` then runs successfully across our entire package.
  
  #### Steps to reproduce the behavior:
  1. Follow README in https://github.com/cquick01/pdoc-test
  2. See errors
  
  ```
  Warn: Error loading test_package:
  Traceback (most recent call last):
    File "/home/cquick/test/venv/lib/python3.10/site-packages/git/__init__.py", line 87, in <module>
      refresh()
    File "/home/cquick/test/venv/lib/python3.10/site-packages/git/__init__.py", line 78, in refresh
      if not FetchInfo.refresh():
    File "/home/cquick/test/venv/lib/python3.10/site-packages/git/remote.py", line 304, in refresh
      if Git().version_info[:2] >= (2, 10):
    File "/home/cquick/test/venv/lib/python3.10/site-packages/git/cmd.py", line 679, in version_info
      return self._version_info
    File "/home/cquick/test/venv/lib/python3.10/site-packages/git/cmd.py", line 638, in __getattr__
      return LazyMixin.__getattr__(self, name)
    File "/home/cquick/test/venv/lib/python3.10/site-packages/gitdb/util.py", line 253, in __getattr__
      self._set_cache_(attr)
    File "/home/cquick/test/venv/lib/python3.10/site-packages/git/cmd.py", line 659, in _set_cache_
      version_numbers = process_version.split(' ')[2]
  IndexError: list index out of range
  
  The above exception was the direct cause of the following exception:
  
  Traceback (most recent call last):
    File "/home/cquick/test/venv/lib/python3.10/site-packages/pdoc/extract.py", line 207, in load_module
      return importlib.import_module(module)
    File "/home/cquick/.pyenv/versions/3.10.6/lib/python3.10/importlib/__init__.py", line 126, in import_module
      return _bootstrap._gcd_import(name[level:], package, level)
    File "<frozen importlib._bootstrap>", line 1050, in _gcd_import
    File "<frozen importlib._bootstrap>", line 1027, in _find_and_load
    File "<frozen importlib._bootstrap>", line 1006, in _find_and_load_unlocked
    File "<frozen importlib._bootstrap>", line 688, in _load_unlocked
    File "<frozen importlib._bootstrap_external>", line 883, in exec_module
    File "<frozen importlib._bootstrap>", line 241, in _call_with_frames_removed
    File "/home/cquick/test/test_package/__init__.py", line 1, in <module>
      import git
    File "/home/cquick/test/venv/lib/python3.10/site-packages/git/__init__.py", line 89, in <module>
      raise ImportError('Failed to initialize: {0}'.format(exc)) from exc
  ImportError: Failed to initialize: list index out of range
  
  The above exception was the direct cause of the following exception:
  
  Traceback (most recent call last):
    File "/home/cquick/test/venv/lib/python3.10/site-packages/pdoc/extract.py", line 250, in walk_packages2
      module = load_module(mod.name)
    File "/home/cquick/.pyenv/versions/3.10.6/lib/python3.10/contextlib.py", line 79, in inner
      return func(*args, **kwds)
    File "/home/cquick/test/venv/lib/python3.10/site-packages/pdoc/extract.py", line 209, in load_module
      raise RuntimeError(f"Error importing {module}") from e
  RuntimeError: Error importing test_package
   (/home/cquick/test/venv/lib/python3.10/site-packages/pdoc/extract.py:252)
  pdoc server ready at http://localhost:8080
  ```
  
  #### System Information
  Paste the output of "pdoc --version" here.
  
  ```
  pdoc --version
  pdoc: 12.0.2
  Python: 3.10.6
  Platform: Linux-5.10.102.1-microsoft-standard-WSL2-x86_64-with-glibc2.35
  ```
  
  Will try to provide more info if needed.