Version bump to 6.2.1

Formalise support for Django 5; drop support for 4.0-4.1

Version bump to 6.1

Remove support for Python 3.5 - 3.6 and Django 2.0 - 2.1

update Github Actions config to test branches other than main

Fill in release date for 5.2

Fill in release date for 5.1

add credit to Martin Sandström

Version bump to 5.0.1

Version bump to 4.4.1