CMake compatibility will be removed

[Fewnity]

With the latest Cmake version, I'm getting warnings when using the toolchain, cmakefiles of the toolchain are getting old and need to update the cmake_minimum_required version to something newer. I won't do it myself with a PR because I don't want to break something.

CMake Deprecation Warning at /usr/local/vitasdk/share/vita.toolchain.cmake:33 (cmake_minimum_required):
Compatibility with CMake < 3.5 will be removed from a future version of CMake.