This now allows tests to be run under a locally built or production
docker image with something like:
`docker run --rm -v $PWD:/usr/src/paperless --entrypoint=bash paperlessngx/paperless-ngx:latest -c "uv run pytest"`
Specific fixes:
- fix unreachable code around `assertRaises` blocks
- fix `assertInt` typos
- fix `str(e)` vs `str(e.exception)` issues
- skip permission-based checks when root (in a docker container)
- catch `OSError` problems when instantiating `INotify` and
skip inotify-based tests when it's unavailable.
