By not providing “Findcatkin.cmake” in CMAKE_MODULE_PATH this project has
asked CMake to find a package configuration file provided by “catkin”, but
CMake did not find one.
Could not find a package configuration file provided by “catkin” with any
of the following names:
catkinConfig.cmake
catkin-config.cmake
原因找不到catkin路径，在终端source 一下 source /opt/ros/melodic/setup.bash(前提装在这里)
或者直接在~/.bashrc中添加 source /opt/ros/melodic/setup.bash 就不用每次重新sourcec了
然后再cmake