Update create.py to support Python3.x
Update create.py to support Python3.x

file() -> open()
dict_obj_A.keys() + dict_obj_B.keys() -> list(dict_obj_A.keys()) + list(dict_obj_B.keys())
PX4/Firmware,krbeverx/Firmware,acfloria/Firmware,PX4/Firmware,PX4/Firmware,PX4/Firmware,PX4/Firmware,krbeverx/Firmware,acfloria/Firmware,acfloria/Firmware,krbeverx/Firmware,acfloria/Firmware,acfloria/Firmware,krbeverx/Firmware,acfloria/Firmware,krbeverx/Firmware,PX4/Firmware,acfloria/Firmware,krbeverx/Firmware,krbeverx/Firmware,PX4/Firmware