[🔥AUDIT🔥] Update to latest gerald-pr action (#86)

🖍 _This is an audit!_ 🖍

## Summary:
This updates our PR workflow. We don't need to tag a new release for this, just closing the loop on the Node 20 update to get rid of Node 16 deprecation.

Issue: FEI-5484

## Test plan:
See that the workflow no longer shows a Node 16 deprecation notice.

Author: somewhatabstract

Auditors: #frontend-infra-web, #github-actions

Required Reviewers:

Approved By:

Checks: ✅ gerald, ✅ autofix, ✅ build_index, ✅ lint_and_unit

Pull Request URL: #86

.github/workflows/gerald-pr.yml

@@ -18,7 +18,7 @@ jobs:
     if: github.event.action != 'edited' || github.event.changes.base != null
     runs-on: ubuntu-latest
     steps:
-      - uses: Khan/actions@gerald-pr-v2
+      - uses: Khan/actions@gerald-pr-v3
         with:
           token: ${{ secrets.GITHUB_TOKEN }}
           admin-token: ${{ secrets.KHAN_ACTIONS_BOT_TOKEN }}