https://docs.djangoproject.com/en/3.1/releases/3.1/
- django.contrib.postgres.fields.JSONField is deprecated and should be
replaced with models.JSONField
- The internals of the implementation in the postgresql backend have
changed a bit in
f48f671223
and thus we need to make an ugly tweak in test_runner.
- app_directories.Loader.get_dirs() now returns a list of PosixPath so
we need to make a small tweak in TwoFactorLoader for that (PosixPath
is not iterable)
Fixes#16010.