chore: Fix upgrade-main.yml GitHub action

.github/workflows/upgrade-main.yml

@@ -4,16 +4,15 @@ on:
   workflow_dispatch: {}
   schedule:
     - cron: 0 9 * * 2 # every Tuesday at 9am
-permissions:
-  contents: write
-  pull-requests: write
 jobs:
   upgrade:
     name: Upgrade
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
         uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8
+        with:
+          ref: main
       - name: Setup Node.js
         uses: actions/setup-node@2028fbc5c25fe9cf00d9f06a71cc4710d4507903
         with:
@@ -22,11 +21,6 @@ jobs:
         run: yarn install --check-files --frozen-lockfile
       - name: Upgrade dependencies
         run: npx projen upgrade
-      - name: Set git identity & add files to commit
-        run: |
-          git config --local user.email [email protected]
-          git config --local user.name svc-apix-bot
-          git add .
       - name: Create Pull Request
         uses: peter-evans/create-pull-request@271a8d0340265f705b14b6d32b9829c1cb33d45e
         with: