chore: Upgrade to node 20 as 16 is EOL soon

[henningmu]

Short description

Node 16 is EOL on 11th September 2023. Nothing will break, but there won't be further security updates. Let's switch 20 (Upcoming LTS).

PR Checklist

• [x] Executed npm run validate and made sure no errors / warnings were shown
• [ ] Described changes in CHANGELOG.md
• [ ] Bumped version in package.json and package-lock.json (npm --no-git-tag-version version <major|minor|patch>) ref

Versioning

Likely going to be a patch release as we increase supported node versions and shouldn't be taking anything away from people running on different node versions.