fix clue.gesture -- enable proximity

Author: jerryneedell

adafruit_clue.py

@@ -550,6 +550,7 @@ def gesture(self):
               print("Gesture: {}".format(clue.gesture))
         """
         self._sensor.enable_gesture = True
+        self._sensor.enable_proximity = True
         return self._sensor.gesture()
 
     @property