fix error when ther is n nixpkgs updates to apply

.github/workflows/auto-update.yml

@@ -31,6 +31,6 @@ jobs:
           git config --global user.name "Alper Çelik (GitHub Actions)"
           git config --global user.email "[email protected]"
           git add flake.lock
-          git commit -m "update nixpkgs"
+          git commit -m "update nixpkgs" || echo "No changes to commit"
           git push origin main