Do not send light_on value to iot bulb set_state (#1090)

Passing this extra value caused the `ignore_default` check in the `IotBulb._set_light_state`
method to fail which causes the device to come back on to the default state.

kasa/iot/modules/light.py

@@ -230,6 +230,8 @@ class Light(IotModule, LightInterface):
                 state_dict["on_off"] = 1
             else:
                 state_dict["on_off"] = int(state.light_on)
+            # Remove the light_on from the dict
+            state_dict.pop("light_on", None)
             return await bulb._set_light_state(state_dict, transition=transition)
 
     @property