Matsee 2way energy meter: revert accidental removal of voltage class

Unintentional removal as part of the bulk change to add translations for
multiple current/voltage/power sensors. Since this just had one voltage
sensor but multiple of the others, it may have triggered an error in the
macro used to do the bulk change.

Issue #2729

custom_components/tuya_local/devices/matsee_2way_energymeter.yaml

@@ -203,6 +203,7 @@ entities:
         mapping:
           - scale: 1000
   - entity: sensor
+    class: voltage
     category: diagnostic
     dps:
       - id: 112