Tech Titans Triumph! Node 18 Bows Out of CI Runs in a Bold Move

In a decisive step towards modernization, the tech community bids adieu to Node 18 as support dwindles, paving the way for the future with cutting-edge versions 20 and 21.

Commit Details:

chore: Remove Node 18 from CI runs (#1945) ## Motivation This has stopped receiving active support (only security updates), and we no longer ship a Node 18 Docker image. ## Change Summary Remove Node 18. ## Merge Checklist _Choose all relevant options below by adding an `x` now or at any time before submitting for review_ - [x] PR title adheres to the [conventional commits](https://www.conventionalcommits.org/en/v1.0.0/) standard - [ ] PR has a [changeset](https://github.com/farcasterxyz/hub-monorepo/blob/main/CONTRIBUTING.md#35-adding-changesets) - [x] PR has been tagged with a change label(s) (i.e. documentation, feature, bugfix, or chore) - [ ] PR includes [documentation](https://github.com/farcasterxyz/hub-monorepo/blob/main/CONTRIBUTING.md#32-writing-docs) if necessary. - [x] All [commits have been signed](https://github.com/farcasterxyz/hub-monorepo/blob/main/CONTRIBUTING.md#22-signing-commits) <!-- start pr-codex --> --- ## PR-Codex overview This PR updates the Node.js versions in the CI workflow to 20 and 21. ### Detailed summary - Updated Node.js versions in CI workflow to 20 and 21 - Removed Node.js version 18 from the matrix configuration > ✨ Ask PR-Codex anything about this PR by commenting with `/codex {your question}` <!-- end pr-codex -->