Fix compile warnings from the ros2_control example

[macmacal]

Description

The good practice of enabling -Werror in #4 showed a problem with an example test code from the ros2_control. There are warnings which are "not ours". We should fixed them ASAP.

References

• Pre-commit config - Ruff, cmake & clang formaters #4
• Point 6 @ https://control.ros.org/humble/doc/ros2_control/hardware_interface/doc/writing_new_hardware_component.html