Pin runs-on Ubuntu 24.04 - #455

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: actions/checkout@v4, nick-fields/retry@14672906e672a08bd6eeb15720e9ed3ce869cdd4, ruby/setup-ruby@a4effe49ee8ee5b8b5091268c473a4628afb5651. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/