v0.4.1: Fix importing apr1

[cognifloyd]

The pythonpath changes in pyproject.toml masked the broken import of apr1. The flat_file backend does not seem to work with v0.4.0 because of this import error. Stevedore just happily skips this bakcend plugin, saying that it is not even available.

You can see some log output from running tools/config_gen.py in pants CI and in legacy ci, and in particular these line:

2025-09-30 01:09:16,189 DEBUG [-] found extension EntryPoint(name='flat_file', value='st2auth_flat_file_backend.flat_file:FlatFileAuthenticationBackend', group='st2auth.backends.backend')
2025-09-30 01:09:16,192 ERROR [-] Could not load 'flat_file': No module named 'apr1'
Traceback (most recent call last):
  File "/home/runner/.cache/pants/named_caches/pex_root/venvs/1/s/9cffbce3/venv/lib/python3.10/site-packages/stevedore/extension.py", line 206, in _load_plugins
    ext = self._load_one_plugin(ep,
  File "/home/runner/.cache/pants/named_caches/pex_root/venvs/1/s/9cffbce3/venv/lib/python3.10/site-packages/stevedore/extension.py", line 240, in _load_one_plugin
    plugin = ep.load()
  ...
  File "/home/runner/.cache/pants/named_caches/pex_root/venvs/1/s/9cffbce3/venv/lib/python3.10/site-packages/st2auth_flat_file_backend/__init__.py", line 18, in <module>
    from .flat_file import FlatFileAuthenticationBackend
  File "/home/runner/.cache/pants/named_caches/pex_root/venvs/1/s/9cffbce3/venv/lib/python3.10/site-packages/st2auth_flat_file_backend/flat_file.py", line 21, in <module>
    import apr1
ModuleNotFoundError: No module named 'apr1'

So, that pythonpath manipulation did not reflect how st2 actually runs the plugins (It does not put the package dir on PYTHONPATH).

I will cut v0.4.1 once this is merged.

[nzlosh]

Good catch!