ROS2 branch needs OpenCV 4 compatibility for ROS2 Foxy on Ubuntu 20.04

[3wnbr1]

Platform

• OS : Ubuntu 20.04 LTS (arm64/amd64)
• ROS Version : Foxy (packages.ros.org)
• libopencv-dev : version 4.2.x

Description Branch ros2 doesn't support opencv4.2 which causes compilation to fail.

In file included from /home/runner/ros_ws/src/costmap_converter/costmap_converter/include/costmap_converter/costmap_to_dynamic_obstacles/multitarget_tracker/Ctracker.h:5,
                 from /home/runner/ros_ws/src/costmap_converter/costmap_converter/include/costmap_converter/costmap_to_dynamic_obstacles/costmap_to_dynamic_obstacles.h:62,
                 from /home/runner/ros_ws/src/costmap_converter/costmap_converter/src/costmap_to_dynamic_obstacles/costmap_to_dynamic_obstacles.cpp:1:
/home/runner/ros_ws/src/costmap_converter/costmap_converter/include/costmap_converter/costmap_to_dynamic_obstacles/multitarget_tracker/Kalman.h:6:10: fatal error: opencv/cv.h: No such file or directory
    6 | #include <opencv/cv.h>
      |          ^~~~~~~~~~~~~
compilation terminated.
make[2]: *** [CMakeFiles/costmap_converter.dir/build.make:132: CMakeFiles/costmap_converter.dir/src/costmap_to_dynamic_obstacles/costmap_to_dynamic_obstacles.cpp.o] Error 1
make[1]: *** [CMakeFiles/Makefile2:147: CMakeFiles/costmap_converter.dir/all] Error 2
make: *** [Makefile:158: all] Error 2

Solution Similar issue fixed by #18 on master, applying PR on ros2 branch or cherry-picking abf10d7979f01e5af1a456e65d5d64dffe1af2ee fixes the issue

[croesmann]

thank you, done!