ref: GroupValues.priority is nullable (#75153)

when models are checked mypy notices several constructions using the
`priority` column which is nullable

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src/sentry/issues/attributes.py

@@ -42,7 +42,7 @@ class GroupValues:
     substatus: int | None
     first_seen: datetime
     num_comments: int
-    priority: int
+    priority: int | None
     first_release_id: int | None