fix(zigbee): Enable the internal pull-up resistor for BUTTON_PIN

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);

libraries/Zigbee/examples/Zigbee_Color_Dimmer_Switch/Zigbee_Color_Dimmer_Switch.ino

@@ -54,7 +54,7 @@ void setup() {
   }
 
   //Init button switch
-  pinMode(SWITCH_PIN, INPUT);
+  pinMode(SWITCH_PIN, INPUT_PULLUP);
 
   //Optional: set Zigbee device name and model
   zbSwitch.setManufacturerAndModel("Espressif", "ZigbeeSwitch");

libraries/Zigbee/examples/Zigbee_On_Off_Light/Zigbee_On_Off_Light.ino

@@ -51,7 +51,7 @@ void setup() {
   digitalWrite(LED_PIN, LOW);
 
   // Init button for factory reset
-  pinMode(BUTTON_PIN, INPUT);
+  pinMode(BUTTON_PIN, INPUT_PULLUP);
 
   //Optional: set Zigbee device name and model
   zbLight.setManufacturerAndModel("Espressif", "ZBLightBulb");

libraries/Zigbee/examples/Zigbee_Temperature_Sensor/Zigbee_Temperature_Sensor.ino

@@ -59,7 +59,7 @@ void setup() {
   }
 
   // Init button switch
-  pinMode(BUTTON_PIN, INPUT);
+  pinMode(BUTTON_PIN, INPUT_PULLUP);
 
   // Optional: set Zigbee device name and model
   zbTempSensor.setManufacturerAndModel("Espressif", "ZigbeeTempSensor");

libraries/Zigbee/examples/Zigbee_Thermostat/Zigbee_Thermostat.ino

@@ -65,7 +65,7 @@ void setup() {
   }
 
   // Init button switch
-  pinMode(BUTTON_PIN, INPUT);
+  pinMode(BUTTON_PIN, INPUT_PULLUP);
 
   // Set callback functions for temperature and configuration receive
   zbThermostat.onTempRecieve(recieveSensorTemp);