Moved busio import inside a try block to save memory

Author: tammymakesthings

adafruit_adxl34x.py

@@ -32,10 +32,11 @@
 
 from micropython import const
 from adafruit_bus_device import i2c_device
-import busio
 
 try:
     from typing import Tuple, Dict
+    # This is only needed for typing
+    import busio # pylint: disable=unused-import
 except ImportError:
     pass