feat(kanchou_petfountain): add compatible product from same source

Issue #5667

custom_components/tuya_local/devices/kanchou_petfountain.yaml

@@ -2,6 +2,8 @@ name: Pet fountain
 products:
   - id: akln8rb04cav403q
     manufacturer: Kanchou
+  - id: kk8qdeaunqdyp8z5
+    manufacturer: Kanchou
   - id: cafirr70niv1hj2x
     manufacturer: Fontanna Smart
     model: FONT7-SMART-B
@@ -112,6 +114,7 @@ entities:
     dps:
       - id: 22
         type: integer
+        optional: true
         name: sensor
         unit: mL
         class: measurement