[CI] DB Migration Checks (#6517)

* Update imports

- Help prevent circular imports

* Run migration checks against 0.13.5

.github/workflows/qc_checks.yaml

@@ -446,6 +446,13 @@ jobs:
           chmod +rw /home/runner/work/InvenTree/db.sqlite3
           invoke migrate
 
+      - name: 0.13.5 Database
+        run: |
+          rm /home/runner/work/InvenTree/db.sqlite3
+          cp test-db/stable_0.13.5.sqlite3 /home/runner/work/InvenTree/db.sqlite3
+          chmod +rw /home/runner/work/InvenTree/db.sqlite3
+          invoke migrate
+
   platform_ui:
     name: Tests - Platform UI
     runs-on: ubuntu-20.04

InvenTree/InvenTree/serializers.py

@@ -25,7 +25,6 @@ from taggit.serializers import TaggitSerializer
 import common.models as common_models
 from common.settings import currency_code_default, currency_code_mappings
 from InvenTree.fields import InvenTreeRestURLField, InvenTreeURLField
-from InvenTree.helpers_model import download_image_from_url, get_base_url
 
 
 class EmptySerializer(serializers.Serializer):
@@ -455,6 +454,8 @@ class UserCreateSerializer(ExendedUserSerializer):
 
     def create(self, validated_data):
         """Send an e email to the user after creation."""
+        from InvenTree.helpers_model import get_base_url
+
         base_url = get_base_url()
 
         instance = super().create(validated_data)
@@ -860,6 +861,8 @@ class RemoteImageMixin(metaclass=serializers.SerializerMetaclass):
         - Attempt to download the image and store it against this object instance
         - Catches and re-throws any errors
         """
+        from InvenTree.helpers_model import download_image_from_url
+
         if not url:
             return