Change heater wattage to 'class: power' instead of hardcoded icon

custom_components/tuya_local/devices/drexma_et7aw_thermostat.yaml

@@ -274,9 +274,9 @@ entities:
           - dps_val: true
             value: °F
   - entity: number
-    category: config
     name: Heater Wattage
-    icon: "mdi:lightning-bolt-circle"
+    class: power
+    category: config
     hidden: true
     dps:
       - id: 116