No checkout in reusable action

Signed-off-by: Charalampos Mainas <charalampos.mainas@gmail.com>

Author: cmainas

.github/workflows/add-git-trailers.yml

@@ -45,9 +45,10 @@ jobs:
           private-key: ${{ secrets.URUNC_BOT_PRIVATE_KEY }}
 
       - name: Append git trailers
-        uses: nubificus/git-trailers@18fd322f3fbfd505b4de728974a4ac1f32f758a7
+        uses: nubificus/git-trailers@9bf4235762fb658e76ce9858fbb97b01ba9f33b8
         with:
           user_info: .github/contributors.yaml
+          user_info: ${{ github.event.pull_request.head.ref }}
 
       - name: Merge PR
         env: