Kokkos version check

[lucbv]

Hi all another issue appears to be the lack of check on the Kokkos Version being used when building against a pre-installed Kokkos library.
I am suspecting that for the time being it works with 4.2.0 and maybe up to 4.0.0 but likely not against anything older than that?
It would be good to add something in CMakeLists.txt to warn users if they attempt to install against an unsupported version.
Also updating the documentation to reflect what is actually supported would be great!

[yasahi-hpc]

Thank you for the comments!
I was not aware of this point, but clearly it is important.
I will add warnings that the insulation against older than version 4.0.0 is not supported.

Documentation will certainly be improved before release!

[cedricchevalier19]

You can put a minimal version with find_package.

[yasahi-hpc]

In addition, I would improve the Versioning in CMake which is added in (#41).