Czajnik kettle: correct type of status sensor

Although it is a sensor, the values are strings.

Issue #403

custom_components/tuya_local/devices/setti_czajnik_kettle.yaml

@@ -236,7 +236,7 @@ secondary_entities:
     category: diagnostic
     dps:
       - id: 15
-        type: integer
+        type: string
         name: sensor
         mapping:
           - dps_val: standby