Rename Django's dev branch to main. (#445)
Rename Django's dev branch to main. (#445)

* Rename Django's dev branch to main.

More information: https://groups.google.com/g/django-developers/c/tctDuKUGosc/
Refs: https://github.com/django/django/pull/14048

* Don't run tests against Django main on Python < 3.8.
jazzband/django-constance,jazzband/django-constance,jezdez/django-constance,jezdez/django-constance,jazzband/django-constance