Update picozero.py

inherit from DigitalInputDevice - makes more semantic sense than Button

Author: pjbRPF

picozero/picozero.py

@@ -1999,7 +1999,7 @@ class Button(Switch):
 Button.when_released = Button.when_deactivated
 
 
-class TouchSensor(Button):
+class TouchSensor(DigitalInputDevice):
     """
     Represents a capacitive touch sensor (e.g. TTP223)