Make sure internal_id None is disregarded (#3667) (patch)

### Fixed

- Discriminator can handle None

cg/services/order_validation_service/models/discriminators.py

@@ -3,5 +3,5 @@
 
 def has_internal_id(v: Any) -> str:
     if isinstance(v, dict):
-        return "existing" if "internal_id" in v.keys() else "new"
+        return "existing" if v.get("internal_id") else "new"
     return "existing" if getattr(v, "internal_id", None) else "new"