Bug in execute_ack

[miquelmassot]

Line 214 in

ros_arduino_bridge/ros_arduino_python/src/ros_arduino_python/arduino_driver.py

Line 241 in a960c8a

attempts += 1

needs to be indented to increase attempts inside the while loop. Otherwise, it will infinitely be looping if the Arduino times out, replies an empty string or "Invalid command".