Bump minimum CMake version
Based on the following warning: CMake Warning (dev) at /home/alex/kde/usr/share/ECM/modules/ECMFindModuleHelpers.cmake:112 (message): Your project should require at least CMake 3.16.0 to use FindKF5.cmake
Based on the following warning: CMake Warning (dev) at /home/alex/kde/usr/share/ECM/modules/ECMFindModuleHelpers.cmake:112 (message): Your project should require at least CMake 3.16.0 to use FindKF5.cmake