Using Github App for check-repos workflow

Signed-off-by: Vacha Shah <vachshah@amazon.com>

.github/workflows/check-repos.yml

@@ -11,22 +11,34 @@ jobs:
   check-project-repos:
     runs-on: ubuntu-latest
     steps:
+      - name: GitHub App token
+        id: github_app_token
+        uses: tibdex/github-app-token@v1.5.0
+        with:
+          app_id: ${{ secrets.APP_ID }}
+          private_key: ${{ secrets.APP_PRIVATE_KEY }}
+          installation_id: 22958780
+
       - uses: actions/checkout@v2
       - name: Update project repositories
         env:
-          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}      
+          GITHUB_TOKEN: ${{ steps.github_app_token.outputs.token }}      
         run: |
           npm install -g meta
           ./scripts/update.sh
           echo REPOS_ADDED=$(git diff --unified=0 .gitignore | grep '+/' | cut -f2 -d'/' | paste -sd ',' - | sed "s/,/, /g" | sed 's/\(.*\),/\1 and/') >> $GITHUB_ENV
+
       - name: Create Pull Request
         uses: peter-evans/create-pull-request@v3
         with:
+          token: ${{ steps.github_app_token.outputs.token }}
           commit-message: Added ${{ env.REPOS_ADDED }}.
+          signoff: true
           delete-branch: true
           title: 'Added ${{ env.REPOS_ADDED }}.'
           body: |
             Added ${{ env.REPOS_ADDED }}.
+
       - name: Check outputs
         run: |
           echo "Pull Request Number - ${{ steps.cpr.outputs.pull-request-number }}"