refactor(settings): Update all references to User to use get_user_model()

ref: #756 closes #755

app/settings/tests/functional/user_settings/test_user_settings_viewset.py

@@ -1,6 +1,7 @@
+import django
 import pytest
 
-from django.contrib.auth.models import Permission, User
+from django.contrib.auth.models import Permission
 from django.contrib.contenttypes.models import ContentType
 from django.shortcuts import reverse
 from django.test import Client, TestCase
@@ -26,6 +27,8 @@ from api.tests.abstract.test_metadata_functional import (
 
 from settings.models.user_settings import UserSettings
 
+User = django.contrib.auth.get_user_model()
+
 
 
 class ViewSetBase: