(SE) v1.8.0 Spack-stack update for upcoming atlas changes

[Dooruk]

Spack-stack v1.8.0 is fully released and tested in NCCS Discover. In this PR, I built a version and run a variational case with SOCA and there were no changes in the answers, I'm waiting on @rtodling to test atmopsheric side:

As a next step we should test building;

• Swell,
• EVA,
• R2D2 v1 and it's dependencies (r2d2 and solo),

And then update the modules here:

https://github.com/GEOS-ESM/swell/blob/develop/src/swell/deployment/platforms/nccs_discover_sles15/modules

One major difference is the use of python 3.11 as I mentioned in this below comment:

#406 (comment)

We could skip SLES12 builds and modules as it is being phased out.

[Dooruk]

Quick note on this:

Spack-stack release 1.8 switches to Python 3.11, this impacts all the Python relevant modulefiles *.lua scripts as we have to update the Python version via this entry:

local pythondir = "python3.10"

to

local pythondir = "python3.11"

So that following works:

prepend_path("PYTHONPATH", pathJoin(base,"lib",pythondir,"site-packages"))