Owon: use string for dps mapping

Issue #616

custom_components/tuya_local/devices/owon_pct513_thermostat.yaml

@@ -146,7 +146,7 @@ primary_entity:
           value: fan
         - dps_val: heatfanon
           value: heating
-        - dps_val: 1
+        - dps_val: "1"
           value: heating
 secondary_entities:
   - entity: number