ci: Address zizmor warnings and bump actions - #17

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: giraffate/clippy-action@13b9d32482f25d29ead141b79e7e04e7900281e0. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/