init support for gitea oauth

I open this MR to get some support to achieve this tasks.

1. Linting is failing. No idea why. It's not realy verbose/helpful 😄
   • https://gitlab.com/markuman/glitchtip-backend/-/jobs/1884597112
2. What do it need to do with glitchtip/urls.py?

Ref: https://django-allauth.readthedocs.io/en/latest/providers.html#gitea