[Bug] Shelly RGBW2 Outputs do not switch off
**Describe the bug**
Outputs cannot be switched off. LED control works fine with dimming to 100%, but 0% is not accepted, lowest value is 1%.


**Environment:**
 - Shelly device(s): [Shelly RGBW2]
 - Plugin version: [v0.19.1]
 - Device running homebridge: [Raspberry Pi, Homebridge v1.6.0]
