feat: add a pattern to UUID as well

openapi/components/schemas/poll.yaml

@@ -1,4 +1,5 @@
 type: object
+
 properties:
   id:
     type: string
@@ -8,6 +9,8 @@ properties:
   uuid:
     type: string
     format: uuid
+    # pattern is defined for implementations that don't understand format: uuid
+    pattern: '[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}'
     description: >
       A Universally Unique IDentifier for the poll. (version 4)
     example: bb788552-727d-470b-827e-d7796248d293