[cmake] Require CMake version 3.5 or newer

[cmake] Require CMake version 3.5 or newer

More recent versions of CMake emit the following warning:
CMake Deprecation Warning at cmake/CMakeLists.txt:10 (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.