Testing with alternative databases

[jacklinke]

Is your feature request related to a problem? Please describe.
Mainly opening this Issue as a reminder about something that might be nice in the future to ensure the package supports users working with a variety of databases, but probably isn't the highest priority right now.

From the runtests.py code comments, it looks like you intend (or intended at one point) to run tests with different databases. This seems like a good idea. I don't have a PR for this (I've not done it before in my projects, but will work on it at some point if you still want it and if you don't get to it first).

Describe the solution you'd like
Tests should be run against database variants commonly used with Django.