Publish CVMFS named snapshots - #276

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: actions/checkout@93ea575cb5d8a053eaa0ac8fa3b40d7e05a33cc8, actions/setup-python@13ae5bb136fac2878aff31522b9efb785519f984. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/