Add hvac modes back to opentherm (#25268)

homeassistant/components/opentherm_gw/climate.py

@@ -130,9 +130,14 @@ class OpenThermClimate(ClimateDevice):
 
     @property
     def hvac_mode(self):
-        """Return current operation ie. heat, cool, idle."""
+        """Return current HVAC mode."""
         return self._current_operation
 
+    @property
+    def hvac_modes(self):
+        """Return available HVAC modes."""
+        return []
+
     @property
     def current_temperature(self):
         """Return the current temperature."""