allow runtests.py to discover tests in django_mongodb/tests

[timgraham]

No description provided.

[aclark4life]

AFAICT this change makes it harder to run the django tests anywhere but on GA?

E.g. https://github.com/aclark4life/just-django/blob/f1c5822bbc7edcd28f869f2ea344a9a168e8ddd7/justfile#L163-L168

I can't run that unless I make changes in a fork of a fork of the django repo …

[timgraham]

No, this is not dependent on GitHub Actions. If you are using a pip install -e version of django-mongodb, the tests directory should be discoverable. If you're getting an error because that directory doesn't exist, perhaps it's because you need to rebase your branch to include the creation of the tests directory (mongodb/django-mongodb-backend#169).

[aclark4life]

Got it, thanks!