build(cmake): bump minimum required to version 3.5

[scribam]

With CMake 3.27, the following deprecation warning is visible:

CMake Deprecation Warning at CMakeLists.txt:1 (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.

Version 3.5 was released in March 2016 and is available on Ubuntu 14.04 (package cmake3) and later