Remove FixLookupAllowedMixin for Django 6.x

[cuthulino]

In Django 6.x the lookup_allowed function takes 4 arguments (it where 3 before).
Therefore filtering on the admin page is no longer working.

django-huey-monitor/huey_monitor/admin.py

Lines 17 to 34 in 56f340c

	class FixLookupAllowedMixin:
	"""
	Work-a-round for: https://code.djangoproject.com/ticket/35020
	# FIXME: Remove after release into all supported Django versions.
	"""
	def lookup_allowed(self, lookup, value):
	list_filter = self._get_list_filter()
	if lookup in list_filter:
	return True
	return super().lookup_allowed(lookup, value)
	def _get_list_filter(self):
	"""return list_filter without `request` object."""
	raise NotImplementedError()
	def get_list_filter(self, request):
	return self._get_list_filter()

My PR completely removes the FixLookupAllowedMixin.
In my opinion it is no longer needed.
Found no error while testing it.

If you want to keep it, I also got a branch where I only fix the error: https://github.com/cuthulino/django-huey-monitor/tree/fix_lookup_allowed

Would be nice to have this in a new verion working with django 6.x

[cuthulino]

@jedie or @phihag
Could you take a look at this?
Thanks.