update-flake-lock: add no-changelog label

Author: nim65s

.github/workflows/update-flake-lock.yml

@@ -16,5 +16,5 @@ jobs:
       - name: Update flake.lock
         uses: DeterminateSystems/update-flake-lock@main
         with:
-          pr-title: "Update flake.lock"
+          pr-labels: "no changelog"
           token: ${{ secrets.GH_TOKEN_FOR_UPDATES }}