Minor changes to make the code compatible with django 4.0
Note that we can't actually upgrade to django 4.0 because that requires
python 3.8, and www.eleves only has python 3.7, so we need to upgrade
www.eleves first.
- Allows login via clipper.
- Default login method (django one) is still available.
- allauth allows user to change and reset his/her password, mails, social
accounts (clipper).
- Signup is managed through allauth.
