[CI] Update github actions to use node.js 20

[youngar]

Warning from our Github actions:

Node.js 16 actions are deprecated. Please update the following actions to use Node.js 20: actions/checkout@v3. For more information see: https://github.blog/changelog/2023-09-22-github-actions-transitioning-from-node-16-to-node-20/.

We have had a similar thing in the past: https://github.com/llvm/circt/pull/5268