[Python] fix python 3 compatibility

example_robot_data/__init__.py

-from robots_loader import (getModelPath, loadHyQ, loadICub, loadTalos, loadTalosArm, loadTalosLegs, loadTiago,
+from .robots_loader import (LoaadTalosLegs, getModelPath, loadHyQ, loadICub, loadTalos, loadTalosArm, loadTiago,
                             loadTiagoNoHand, readParamsFromSrdf)