Set cmake_minimum_required first as recommended in the documentation

https://cmake.org/cmake/help/latest/command/cmake_minimum_required.html


"Note Call the cmake_minimum_required() command at the beginning of the top-level CMakeLists.txt file even before calling the project() command. It is important to establish version and policy settings before invoking other commands whose behavior they may affect."

Signed-off-by: Pierre Hallot <hallotpierre@gmail.com>