Bump Python requirement Django to 4.1.4

• Requires ponos!348 and ponos!377

• Requires a git tag base-django-4.1.4 to build the new base image.

• Closes #998 (closed), #999 (closed)

• Removed all the default_app_config because they have been completely removed from this release and were deprecated before.

• The update changes all SELECT (1) as "a" to SELECT 1 as "a", which has no effect on the actual queries but changes the SQL validation.

• The USE_L10N setting has been removed because it is deprecated and will be removed in Django 5.0, and defaults to True anyway.

• The name= on cached_property has been removed because it was only needed for Python ≤ 3.6.

• TestCase.assertQuerysetEqual has supported comparisons without repr() for a while, but now it no longer supports old comparisons with repr() at all.

• Fixed a DRF deprecation warning on the set_context method of custom serializer defaults as it could cause race conditions; replaced it with requires_context.

• ⚠ 1 warning remaining that would cause manage.py check calls to fail (and therefore the infra script will break):

  documents.MetaData: (models.W045) Check constraint 'metadata_numeric_values' contains RawSQL() expression and won't be validated during the model full_clean().
    HINT: Silence this warning if you don't care about it.

  This is part of #1001 (closed).