build: require cmake >= 3.5

[orbea]

With cmake-3.27.9:

CMake Deprecation Warning at CMakeLists.txt:17 (cmake_minimum_required):
  Compatibility with CMake < 3.5 will be removed from a future version of
  CMake.

  Update the VERSION argument <min> value or use a ...<max> suffix to tell
  CMake that the project does not need compatibility with older versions.

[orbea]

@Grumbel If you have time I would really appreciate if you can review this.