Migrate to Rocky8 installation of spack-stack on Jet (#61)

- Update Jet module file to use Rocky8 installation of spack-stack;
- Jet has been upgraded to the Rocky8 Linux OS and present module file
no longer works
  Resolves #60
  Refs NOAA-EMC/global-workflow#2377

modulefiles/gfsutils_jet.intel.lua

@@ -2,7 +2,7 @@ help([[
 Build environment for GFS utilities on Jet
 ]])
 
-prepend_path("MODULEPATH", "/lfs4/HFIP/hfv3gfs/role.epic/spack-stack/spack-stack-1.6.0/envs/gsi-addon-dev/install/modulefiles/Core")
+prepend_path("MODULEPATH", "/lfs4/HFIP/hfv3gfs/role.epic/spack-stack/spack-stack-1.6.0/envs/gsi-addon-dev-rocky8/install/modulefiles/Core")
 
 local stack_intel_ver=os.getenv("stack_intel_ver") or "2021.5.0"
 local stack_impi_ver=os.getenv("stack_impi_ver") or "2021.5.1"