Add support for Django 4 and (maybe?) drop support for 1.11

[renatooliveira]

Hi team, I'm using it on a project I'm working on with Django 4, it seems to work fine, and I've run the tests against 4.1, it all pass. Is it ok if I send a PR?

Also, django 1.11 is not supported anymore, as of python 2.7. Should we drop support for it?

I'm ready to do a PR once the issue is accepted

cc @caioariede

Checklist

• [ ] I have verified that that issue exists against the master branch of django-anon
• [x] I have searched for similar issues in both open and closed tickets and cannot find a duplicate
• [x] I have reduced the issue to the simplest possible case
• [ ] I have included a failing test as a pull request (If you are unable to do so we can still accept the issue)

[caioariede]

@renatooliveira yes please, that would be great!