Make get_dfu_devices compatible with pyusb 1.0.0b2
Make get_dfu_devices compatible with pyusb 1.0.0b2

kwagyeman/openmv,SmartArduino/openmv,kwagyeman/openmv,SmartArduino/openmv,tianzhihen/openmv,kwagyeman/openmv,iabdalkader/openmv,openmv/openmv,iabdalkader/openmv,openmv/openmv,iabdalkader/openmv,tianzhihen/openmv,SmartArduino/openmv,openmv/openmv,tianzhihen/openmv,iabdalkader/openmv,kwagyeman/openmv,SmartArduino/openmv,tianzhihen/openmv,openmv/openmv