message: use spack branch
diff: {
  "package_name": "axom",
  "package_version": "develop",
  -"package_final_phase" : "hostconfig",
  +"package_final_phase": "initconfig",
  "package_source_dir": "../..",
  "spack_url": "https://github.com/spack/spack",
  -"spack_commit": "e4c1cb380beb088393e47ba9caa27a2e5953b4db",
  +"spack_branch": "features/cached-cmake-build-system",
  "spack_configs_path": "scripts/spack/configs",
  "spack_packages_path": "scripts/spack/packages",
  "vcpkg_url": "https://github.com/microsoft/vcpkg",
  