www/py-dj51-django-allauth: New port

Clone of existing port for Django 5.1.

Compared to py-django-allauth, this updates to the
latest version and enables MFA by default.

Did not want to push this onto sunpoet@, so currently
I'm the maintainer. Please feel free to take the port
from me without asking.

PR: 286533
Co-authored-by: Sebastian <sko@rostwald.de>