cmake problem

Hello
  When I compile the mpc-flow-cpp, I got some error in cmake like "policy known" and others. I found the solution in there:  https://stackoverflow.com/questions/26838367/cmake-attempted-to-add-link-library-to-target-which-is-not-built-in-this-direct

So maybe we should change the cmake_minimum_required to 3.13?
(err in 3.10.2, I upgrade to 3.27.1 and succeed)