Upgrade GitHub Actions

[cclauss]

• https://github.com/actions/checkout/releases is v6.0.2
• https://github.com/actions/setup-python/releases is v6.2.0

[bastibe]

Thank you for the pull request. It does not appear to work completely, some tests fail. Do you know what's up with that?

[bastibe]

The windows-latest/x86 failure should be fixed if you rebase onto master.

[bastibe]

This looks good now. Thank you.

Can you tell me why we should upgrade these actions? The old ones seem to work fine. I'm just asking out of curiosity.

Is this ready to merge from your end?

[cclauss]

Software supply chain attacks have become quite serious and running on end-of-life software will increase attack surface.

Fixes these annotations on the previous GitHub Action runs:

Warning: Node.js 20 actions are deprecated. The following actions are running on Node.js 20 and may not work as expected: actions/checkout@v2. Actions will be forced to run with Node.js 24 by default starting June 16th, 2026. Node.js 20 will be removed from the runner on September 16th, 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/

[cclauss]

Ready to merge.

[bastibe]

Thank you very much!