Taken from:
commit a2bcd795ed68d0b5882e853e731624f572cbb28e
Author: Adam Johnson <me@adamj.eu>
Date: Sun Apr 28 23:08:54 2019 +0100
Support Django 2.2 and stop RemovedInDjango30Warning (#13)
* Add HISTORY note and update README
* Add 2.2 to tox testing grid
* Update `classifiers` in `setup.py`
without the related documentation/build changes.