add regular builds against latest spack version

We should regularly build magix3d using the latest release of spack in order to plan the necessary adjustments.

Most llikely https://github.com/LIHPC-Computational-Geometry/spack_recipes/actions/runs/16743230800/job/47396227861 fails because `spack-1.0.0` was released two weeks ago and our `check-push.yml` workflow builds against spack-latest, which fails but was unnoticed.