[🔥AUDIT🔥] Fix the label functionality. (#96)

🖍 _This is an audit!_ 🖍

## Summary:
The way I implemented it before didn't work well with REVIEWERS.  Now
it's a bit more complicated but also more principled.

Issue: https://khanacademy.atlassian.net/browse/FEI-5970

## Test plan:
The comments and such on Khan/gerald#90

Author: csilvers

Auditors: #github-actions, jeresig, lillialexis

Required Reviewers:

Approved By:

Checks: ⌛ Lints, ⌛ gerald

Pull Request URL: #96

Author: csilvers

.changeset/tidy-mails-begin.md

@@ -0,0 +1,5 @@
+---
+"gerald-pr": patch
+---
+
+Fixed the label fucntionality

actions/gerald-pr/action.yml

@@ -25,7 +25,7 @@ runs:
           ref: '${{ github.head_ref }}'
         if: ${{ github.event.pull_request.draft == false }}
       - name: Run Gerald
-        uses: Khan/gerald@v4.2
+        uses: Khan/gerald@v4.3
         env:
           GITHUB_TOKEN: '${{ inputs.token }}'
           ADMIN_PERMISSION_TOKEN: '${{ inputs.admin-token }}'