Bstuoky keypad: make doorbell optional

Since this is a button/event, it makes sense that it would not always be sent
by the device.

Issue #1152

custom_components/tuya_local/devices/bstuokey_access_keypad.yaml

@@ -112,6 +112,7 @@ secondary_entities:
       - id: 101
         type: boolean
         name: event
+        optional: true
         mapping:
           - dps_val: true
             value: ring
@@ -125,6 +126,7 @@ secondary_entities:
       - id: 101
         type: boolean
         name: sensor
+        optional: true
   - entity: switch
     name: Beep on error
     category: config