Move pytest.ini to mounted folder, change pytest cache dir

[AetherUnbound]

Description of Changes

This PR fixes an issue I've been experiencing where running pytest in the container will create a .pytest_cache folder as root which prevents the container from being rebuilt.

$ just build
docker-compose --file=docker-compose.yml --file=docker-compose.dev.yml build
postgres uses an image, skipping
minio uses an image, skipping
createbucket uses an image, skipping
Building web
error checking context: 'can't stat '/home/aether/git/OpenOversight/OpenOversight/.pytest_cache''.
ERROR: Service 'web' failed to build
error: Recipe `build` failed on line 21 with exit code 1

This PR changes the cache directory to something that isn't mounted.

Notes for Deployment

Screenshots (if appropriate)

Tests and linting

• I have rebased my changes on main

• just lint passes

• just test passes

[sarayourfriend]

LGTM, but the PR title doesn't make sense to me... should it be "Move pytest cache outside mounted folder"?

[AetherUnbound]

Ah, it might not be clear from the diff but I'm also moving where the pytest.ini file is. I'll change the title to reflect both!

[AetherUnbound]

Gah it didn't keep the title change!!! 😡