Move spack CI into reusable as well

Author: mathomp4

.github/workflows/spack-ci.yml

@@ -25,3 +25,9 @@ jobs:
     with:
       compiler: ${{ matrix.compiler }}
       cmake-build-type: ${{ matrix.build-type }}
+
+  spack_build:
+    uses: GEOS-ESM/CI-workflows/.github/workflows/spack_gcc_build.yml@project/geosgcm
+    secrets:
+      BUILDCACHE_USERNAME: ${{ secrets.BUILDCACHE_USERNAME }}
+      BUILDCACHE_TOKEN: ${{ secrets.BUILDCACHE_TOKEN }}