GitHub CI starts deprecating old actions/*:

Warning: Node.js 20 actions are deprecated. The following actions are running on Node.js 20 and may not work as expected: actions/checkout@v4, actions/setup-node@v4, actions/upload-artifact@v4. Actions will be forced to run with Node.js 24 by default starting June 2nd, 2026. Please check if updated versions of these actions are available that support Node.js 24. To opt into Node.js 24 now, set the FORCE_JAVASCRIPT_ACTIONS_TO_NODE24=true environment variable on the runner or in your workflow file. Once Node.js 24 becomes the default, you can temporarily opt out by setting ACTIONS_ALLOW_USE_UNSECURE_NODE_VERSION=true. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/

from a recent CI run: https://github.com/babel/babel/actions/runs/23448031036/job/68217183015.

In this PR we bumped all actions/* CI dependencies, where

cache is upgraded from v4 to v5
checkout is upgraded from v4 to v6
download-artifact is upgraded from v4 to v8
setup-node is upgraded from v4 to v6
upload-artifact is upgraded from v4 to v7

If the CI passes, I will create a similar PR for the 7.x branch.