For RGBW over MQTT, card sends white_value, which is deprecated

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For an RGBW MQTT light, configurations with white_value = true in configuration.yaml give an error in HA

the expected formats are:
rgbw_state_topic string (optional)
The MQTT topic subscribed to receive RGBW state updates. The expected payload is the RGBW values separated by commas, for example, 255,0,127,64.

or, for JSON, a key in the format:
"color":{"r":0,"g":121,"b":6,"w":255}

When you select a value with the White slider, HA throws an error saying white_value is undefined

Really nice widget, hope you have time to pick this issue up!