Add battery attribute to Sensibo (#14735)

* Added battery attribute

* Simplify current_battery

homeassistant/components/climate/sensibo.py

@@ -154,7 +154,8 @@ class SensiboClimate(ClimateDevice):
     @property
     def device_state_attributes(self):
         """Return the state attributes."""
-        return {ATTR_CURRENT_HUMIDITY: self.current_humidity}
+        return {ATTR_CURRENT_HUMIDITY: self.current_humidity,
+                'battery': self.current_battery}
 
     @property
     def temperature_unit(self):
@@ -191,6 +192,11 @@ class SensiboClimate(ClimateDevice):
         """Return the current humidity."""
         return self._measurements['humidity']
 
+    @property
+    def current_battery(self):
+        """Return the current battery voltage."""
+        return self._measurements.get('batteryVoltage')
+
     @property
     def current_temperature(self):
         """Return the current temperature."""