Fix CMake minimum require version warning

[nate-plxs]

The cmake_minimum_required specified in the parent CMakeLists.txt file is far enough out of date that it triggers a CMake warning starting in CMake 3.27, see docs

This can be fixed, by at a minimum bumping to cmake_minimum_required(VERSION 3.5.0 FATAL_ERROR).

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.