Update actions/setup-node action to v6

Author: renovate[bot]

.github/workflows/validate-config.yml

@@ -9,7 +9,7 @@ jobs:
       - name: Checkout
         uses: actions/checkout@v5
       - name: Setup Node
-        uses: actions/setup-node@v5
+        uses: actions/setup-node@v6
         with:
           node-version: lts/*
       - name: Restore cache