Django-generic-filters

* Fix how choice value is retrieved on the get_filters() for django3 (68) pleasedontbelong
* Publish workflow should just run on tag push (66) ewjoachim
* Create CODEOWNERS (65) ewjoachim

Kudos:

ewjoachim, mike-perdide and pleasedontbelong

* Fixing Django 4.0 definition in tox.ini (64) mike-perdide
* Django compat: 3.1, 3.2, 4.0 (63) ewjoachim

Kudos:

ewjoachim and mike-perdide

- Fix a lot of slightly broken things in the packaging and boilerplate, test the
lib for real on recent python/django versions (62)

- Add support for Django 2.2 & 3.0
- Drop support for Django 1.8, 1.9 & 1.10

- Make choice label optionaly safely rendered in html

- Fix pep8 issues. Replace sqlite database by postgresql in demo settings (more strict)
- Fix HiddenWidget issue with (Model)MultipleChoiceField
- Fix IS NULL filter issue when fields are empty (None, [] or empty queryset)
- Generate "model"."column" IN (...) instead of "model"."colunm" = [...]
- Improve FilterView tests for (Multiple)ModelChoices and (Multiple)Choices fields