ci: set PR auto merge version bump PR (#146)

Author: fmenezes

.github/workflows/prepare_release.yaml

@@ -16,12 +16,12 @@ jobs:
   create-pr:
     runs-on: ubuntu-latest
     steps:
+      - uses: GitHubSecurityLab/actions-permissions/monitor@v1
       - uses: mongodb-js/devtools-shared/actions/setup-bot-token@main
         id: app-token
         with:
           app-id: ${{ vars.DEVTOOLS_BOT_APP_ID }}
           private-key: ${{ secrets.DEVTOOLS_BOT_PRIVATE_KEY }}
-      - uses: GitHubSecurityLab/actions-permissions/monitor@v1
       - uses: actions/checkout@v4
       - uses: actions/setup-node@v4
         with:
@@ -45,3 +45,8 @@ jobs:
           branch: chore_release_${{ steps.bump-version.outputs.NEW_VERSION }}
           author: "${{ steps.app-token.outputs.app-slug}}[bot] <${{ steps.app-token.outputs.app-email }}>"
           committer: "${{ steps.app-token.outputs.app-slug}}[bot] <${{ steps.app-token.outputs.app-email }}>"
+      - name: Set auto merge
+        env:
+          GH_TOKEN: ${{ steps.app-token.outputs.token }}
+        run: |
+          gh pr merge ${{ steps.create-pr.outputs.pull-request-number }} --auto --squash