Fix Django 3.1 deprecation removal problems

- FieldDoesNotExist now has to be imported from django.core.exceptions
- Django docs specifically say not to import
  django.conf.global_settings, which now has the side-effect of
  triggering one of the check errors

awx/main/tests/unit/api/test_filters.py

@@ -2,7 +2,11 @@
 
 import pytest
 
+# Django
+from django.core.exceptions import FieldDoesNotExist
+
 from rest_framework.exceptions import PermissionDenied, ParseError
+
 from awx.api.filters import FieldLookupBackend, OrderByBackend, get_field_from_path
 from awx.main.models import (
     AdHocCommand,
@@ -22,9 +26,6 @@ from awx.main.models import (
 from awx.main.models.oauth import OAuth2Application
 from awx.main.models.jobs import JobOptions
 
-# Django
-from django.db.models.fields import FieldDoesNotExist
-
 
 def test_related():
     field_lookup = FieldLookupBackend()