GW submodules no longer building on Gaea-C5 after OS upgrade; Also add Gaea-C6 build

[DavidBurrows-NCO]

What is wrong?

The Gaea-C5 OS upgrade updated version numbers for PrgEnv-intel, craype, and intel-classic, which are prerequisites for spack-stack-1.6.0.

What should have happened?

spack-stack-1.6.0 should load within submodules and workflow/gw_setup.sh script.

What machines are impacted?

All or N/A

What global-workflow hash are you using?

develop

Steps to reproduce

1. clone GW
2. cd sorc
3. ./build_*.sh
   All submodules fail.

Additional information

No response

Do you have a proposed solution?

EPIC SI team is working on re-installing spack-stack-1.6.0. It should be completed by 20241017.