Node 16 actions deprecated

[lnlyssg]

FYI you will need to update the GitHub workflows to newer actions (where available) as per https://github.blog/changelog/2023-09-22-github-actions-transitioning-from-node-16-to-node-20/

I'm seeing the below message on a recent run:

Node.js 16 actions are deprecated. Please update the following actions to use Node.js 20: actions/checkout@v3, actions/setup-python@v4, dawidd6/action-download-artifact@v2.

I believe all of these actions have newer versions that use Node 20