Cleans up CMakeLists.txt a little bit
Cleans up CMakeLists.txt a little bit

* Only one cmake_minimum_required() per project.
* Prepending our module location to CMAKE_MODULE_PATH is no longer needed.
* ${PROJECT_NAME} isn't need anymore in the source code.

ThomasVie/lxqt-runner,stefonarch/lxqt-runner,lxde/lxqt-runner,rbazaud/lxqt-runner