Increasing minimum CMake version causes problems on install

[lobis]

When working on #129 I noticed that the pipeline was not passing due to the installation directory missing some files (the binaries and libraries). After much trial and error, I found that the problem was that I had increased the minimum required version of CMake. After reverting this change, it was fixed 848f2da.

However since #129 is using some new features of CMake (and perhaps other code is already doing the same), having 3.5 as the minimum CMake version (which is from 6 years ago), will probably lead to problems on systems that use a cmake version closer to 3.5.

I vote to bump the minimum CMake version to 3.16, but in order to do that we need to fix this issue.

[juanangp]

This issue seems related to a cmake bug, which was introduced in version 3.14 and seems resolved after version 3.21, this last point I didn't check properly. Seems related with cmake policy CMP0082 https://cmake.org/cmake/help/latest/policy/CMP0082.html and it is weird since it depends on the cmake_minimum_version required and not the cmake version which is used to compile the code.
For more details on this cmake bug check https://gitlab.kitware.com/cmake/cmake/-/issues/22234

There are two solutions to fix this issue:

• Use older CMP0082 policy, that should be added at the beggining of the CMakeList.txt:

if(${CMAKE_VERSION} VERSION_LESS "3.21") 
    cmake_policy(SET CMP0082 OLD)
endif()

• The other solution is to place add_subdirectory command after any install command in the CMakeList.txt

Let me know how do you want to proceed.