fix: make deviceaccess optional

Python_script/deviceaccess_measurement.py

 
 import dut_measurement
-import deviceaccess
+try:
+    import deviceaccess
+except ImportError:
+    print('### WARNING: Could not import module \'deviceaccess\'.' +
+          ' Using the DeviceAccessMeasurement will cause exceptions! ###')
 import numpy
 
-
 class DeviceAccessMeasurement(dut_measurement.DutMeasurement):
     def __init__(self, config_data):