Node.js 20 is deprecated

This is a warning consistently showing during the GitHub Action that runs the tests:
> Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: actions/cache@v4, actions/checkout@v4, actions/setup-python@v5. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/

Should presumably update the versions for those actions so they natively use Node.js 24 or higher.

Start by locating the GitHub Actions workflow that runs the tests and inspect its references to actions/cache@v4, actions/checkout@v4, and actions/setup-python@v5. Update the referenced action versions as appropriate, then run the test workflow and confirm the Node.js deprecation warning no longer appears.

Written by the indexing model from the issue text.