Owon PCT513: add additional pre-heat mapping

Although other hvac_action values are text, it appears that there is a pre-heat
state which is indicated as "1".

Issue #616

custom_components/tuya_local/devices/owon_pct513_thermostat.yaml

@@ -146,6 +146,8 @@ primary_entity:
           value: fan
         - dps_val: heatfanon
           value: heating
+        - dps_val: 1
+          value: heating
 secondary_entities:
   - entity: number
     name: Fan runtime