Modify README workflow so that the PR is created by a bot (#5251)

Author: rzuckerm

.github/workflows/readme.yml

@@ -24,6 +24,12 @@ jobs:
 
     runs-on: ubuntu-latest
     steps:
+    - uses: actions/create-github-app-token@v1
+      id: generate-token
+      with:
+        app-id: ${{ secrets.README_BOT_APP_ID }}
+        private-key: ${{ secrets.README_BOT_PRIVATE_KEY }}
+
     - uses: actions/checkout@v4
 
     - name: Read repo config
@@ -53,16 +59,17 @@ jobs:
       uses: peter-evans/create-pull-request@v7
       with:
         commit-message: Regenerated READMEs
-        committer: GitHub Actions <action@github.com>
+        author: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
         branch: readme-generation
         delete-branch: true
         title: '[Automated Workflow] Add/Modify READMEs'
         labels: enhancement
-        token: ${{ secrets.PAT }}
+        token: ${{ steps.generate-token.outputs.token }}
 
     - name: Enable Pull Request Automerge
       if: steps.cpr.outputs.pull-request-operation == 'created'
       uses: peter-evans/enable-pull-request-automerge@v3
       with:
         pull-request-number: ${{ steps.cpr.outputs.pull-request-number }}
         merge-method: squash
+        token: ${{ steps.generate-token.outputs.token }}