Beca BHT002: make dp 4 optional

Issue #950

custom_components/tuya_local/devices/beca_bht002_thermostat_c.yaml

@@ -1,4 +1,7 @@
-name: BHT-002 thermostat external C
+name: Thermostat
+products:
+  - id: IAYz2WK1th0cMLmL
+    name: Beca BHT-002
 primary_entity:
   entity: climate
   dps:
@@ -15,6 +18,9 @@ primary_entity:
               value: auto
             - dps_val: "1"
               value: heat
+            - dps_val: null
+              value: heat
+              hidden: true
     - id: 2
       type: integer
       name: temperature
@@ -31,6 +37,7 @@ primary_entity:
     - id: 4
       type: string
       name: mode
+      optional: true
       hidden: true
     - id: 5
       type: boolean