python: remove lib prefix for the Python wrapper

bindings/python/CMakeLists.txt

bindings/python/pinocchio/__init__.py

bindings/python/pinocchio/deprecated.py

bindings/python/pinocchio/explog.py

bindings/python/pinocchio/robot_wrapper.py

bindings/python/pinocchio/romeo_wrapper.py

bindings/python/pinocchio/shortcuts.py

bindings/python/pinocchio/utils.py

bindings/python/pinocchio/visualize/base_visualizer.py

bindings/python/pinocchio/visualize/gepetto_visualizer.py

bindings/python/pinocchio/visualize/meshcat_visualizer.py

bindings/python/pinocchio/visualize/panda3d_visualizer.py