add targets for more consistent caching

Author: rem1776

.github/workflows/github_cmake_nvhpc.yml

@@ -25,6 +25,8 @@ jobs:
       uses: spack/setup-spack@v3.0.0
       with:
         buildcache: true
+        spack_ref: releases/v1.1.1
+        paackages_ref: v2026.03.0
     - name: Set up custom build cache and build compiler
       run: |
         spack mirror add \
@@ -33,11 +35,11 @@ jobs:
             --oci-password-variable REGISTRY_TOKEN \
             rem-gh-cache oci://ghcr.io/rem1776/ci-cache-ubuntu
         spack compiler find
-        spack install nvhpc
+        spack install nvhpc target=x86_64
     - name: Install dependencies
       run: |
         spack compiler find
-        spack install netcdf-fortran %nvhpc mpich %nvhpc libyaml %nvhpc
+        spack install netcdf-fortran%nvhpc mpich%nvhpc libyaml%nvhpc target=x86_64
     - name: Configure
       run: |
         . /home/runner/work/FMS/FMS/spack/share/spack/setup-env.sh