Fix HAVCAction typing in Balboa Spa Client (#94658)

homeassistant/components/balboa/climate.py

@@ -78,7 +78,7 @@ class BalboaClimateEntity(BalboaEntity, ClimateEntity):
         return HEAT_HVAC_MODE_MAP.get(self._client.heat_mode.state)
 
     @property
-    def hvac_action(self) -> str:
+    def hvac_action(self) -> HVACAction:
         """Return the current operation mode."""
         return HEAT_STATE_HVAC_ACTION_MAP[self._client.heat_state]