Fix NEUT 6 compilation (cmake)

[KSkwarczynski]

Main problem lies in fact that Nuisance uses hacks in NuHepMC/CMakeModules and here it calls:

nuisance/cmake/Modules/NUISANCEDependencies.cmake

Line 122 in 3f80843

include(NEUT)

which is implemented here:
https://github.com/NuHepMC/CMakeModules/blob/main/NEUT.cmake

NEUT 6 has proper cmake and all these hacks are completely not needed.
What I think would be solution is to update NEUT.cmake that if if(NEUT_VERSION VERSION_GREATER 6.0.0) simmply call find_package.

I am happy to fix it but I have no control over
https://github.com/NuHepMC/CMakeModules/blob/main/NEUT.cmake

Somone (@luketpickering ?) would have to help me.

I can also make this check on Nuiscane level.

Issue observed by Kasturi Vedantha Srinivas