build(deps): bump spack/setup-spack from 2 to 3

Bumps [spack/setup-spack](https://github.com/spack/setup-spack) from 2 to 3.
- [Release notes](https://github.com/spack/setup-spack/releases)
- [Changelog](https://github.com/spack/setup-spack/blob/main/CHANGELOG.md)
- [Commits](https://github.com/spack/setup-spack/compare/v2...v3)

---
updated-dependencies:
- dependency-name: spack/setup-spack
  dependency-version: '3'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

.github/workflows/buildcache.yml

@@ -61,7 +61,7 @@ jobs:
       - uses: actions/checkout@v6
 
       - name: Setup spack
-        uses: spack/setup-spack@v2
+        uses: spack/setup-spack@v3
         with:
           ref: v1.1.0
           color: true