chore(deps): truncate Dependabot PR bodies to the Signed-off-by line only and skip the remainder (#1120)

Author: jenstroeger

.github/workflows/dependabot-automerge.yaml

@@ -14,7 +14,9 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - name: Merge Dependabot PR
-      run: gh pr merge --squash --delete-branch "$PR_URL"
+      run: |
+        BODY=$(gh pr view --json commits --jq .commits[0].messageBody "$PR_URL" | grep Signed-off-by)
+        gh pr merge --squash --delete-branch --body "$BODY" "$PR_URL"
       env:
         PR_URL: ${{ github.event.pull_request.html_url }}
         GITHUB_TOKEN: ${{ secrets.DEPENDABOT_AUTOMERGE_TOKEN }}