www/py-{dj21,dj22}-django-filter: Update to 2.2.0
Changelog:
- Added DjangoFilterBackend.get_schema_operation_parameters() for DRF 3.10+
- OpenAPI schema generation
- Added lookup_expr to MultipleChoiceFilter
- Dropped support for EOL Python 3.4
https://github.com/carltongibson/django-filter/releases/tag/2.2.0