Update integrate_llvm.yml

Author: makslevental

.github/workflows/integrate_llvm.yml

@@ -83,7 +83,7 @@ jobs:
           
           git config user.email "github-actions[bot]@users.noreply.github.com"
           git config user.name "github-actions[bot]"
-          git pull /tmp/llvm-project main --no-rebase
+          git pull /tmp/llvm-project main --no-rebase --ff
 
       - name: Generate token
         uses: actions/create-github-app-token@v1