models: Extract db into own file to prevent circular dependency

server/entertainment_decider/models/__init__.py

@@ -8,6 +8,10 @@ from .custom_types import (
     SafeStr,
 )
 
+from .db import (
+    db,
+)
+
 from .entities import (
     CollectionStats,
     CollectionUriMapping,
@@ -20,7 +24,6 @@ from .entities import (
     Tag,
     Tagable,
     TagKey,
-    db,
 )
 
 from .predefined_tags import (

server/entertainment_decider/models/db.py

@@ -0,0 +1,4 @@
+from pony import orm
+
+
+db = orm.Database()

server/entertainment_decider/models/entities.py

@@ -18,13 +18,13 @@ import requests
 from pony import orm
 
 from .custom_types import Query
+from .db import db
 from .thumbnails import THUMBNAIL_ALLOWED_TYPES, THUMBNAIL_HEADERS
 from .extras import (
     UriHolder,
 )
 from ..preferences.tag_protocol import TagableProto, TagProto
 
-db = orm.Database()
 
 
 T = TypeVar("T")