feat(security): add ClamAV integration

[Yelinz]

This adds django_clamd for AV scanning capabilites with ClamAV.
The scanning can be enabled through the settings.

[winged]

Small nitpick about config defaults.

Also, for new features, I'd like to see a short description in the commit message and pull request to explain a bit more what it does. Generally I'd like to see less one-liners (this is not a personal feedback, just a general observation)

[winged]

Docs should match code. And it's a pity the pyproject.toml got shuffled around, even though no actual change happend there despite the new dependency. Especially the coverage config which is entirely unrelated to this change.