Update Zigbee_Color_Dimmable_Light.ino

Configure BUTTON_PIN as an input and enable the internal pull-up resistor

Author: lboue

Diff for: libraries/Zigbee/examples/Zigbee_Color_Dimmable_Light/Zigbee_Color_Dimmable_Light.ino

@@ -65,7 +65,7 @@ void setup() {
   rgbLedWrite(LED_PIN, 0, 0, 0);
 
   // Init button for factory reset
-  pinMode(BUTTON_PIN, INPUT);
+  pinMode(BUTTON_PIN, INPUT_PULLUP);
 
   // Set callback function for light change
   zbColorLight.onLightChange(setRGBLight);