Gautone alarm: Make mode notification switch optional

Seems this is not always reported.

Issue #1194

custom_components/tuya_local/devices/gautone_pg103_alarm.yaml

@@ -91,6 +91,7 @@ secondary_entities:
       - id: 10
         type: boolean
         name: switch
+        optional: true
   - entity: switch
     name: Alarm notification
     category: config