CI: update misc actions

[emilk]

What

We get a lot of these warnings on CI:

Node.js 16 actions are deprecated. Please update the following actions to use Node.js 20: …

This attempts to fix those

Checklist

• I have read and agree to Contributor Guide and the Code of Conduct
• I've included a screenshot or gif (if applicable)
• I have tested the web demo (if applicable):
  • Using newly built examples: rerun.io/viewer
  • Using examples from latest main build: rerun.io/viewer
  • Using full set of examples from nightly build: rerun.io/viewer
• The PR title and labels are set such as to maximize their usefulness for the next release's CHANGELOG
• If applicable, add a new check to the release checklist!

• PR Build Summary
• Recent benchmark results
• Wasm size tracking

[github-actions]

Deployed docs

Commit	Link
061f119	https://landing-64sksx6yw-rerun.vercel.app/docs