fix: Apply allOf pattern to v2.11 createConversation response

Missed in the initial update — v2.11 inherits
AddConversationIdToUserMessageResponse from v2.2 and its example
already includes conversation_id: '363'.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: markdennis22

descriptions/2.11/api.intercom.io.yaml

@@ -4474,7 +4474,10 @@ paths:
                     message_type: inapp
                     conversation_id: '363'
               schema:
-                "$ref": "#/components/schemas/message"
+                allOf:
+                - "$ref": "#/components/schemas/message"
+                required:
+                - conversation_id
         '404':
           description: Contact Not Found
           content: