chore: update actions/setup-node action to v6

Author: renovate[bot]

.github/workflows/CI.yml

@@ -13,7 +13,7 @@ jobs:
     - name: Checkout
       uses: actions/checkout@v5
     - name: Use Node.js
-      uses: actions/setup-node@v5
+      uses: actions/setup-node@v6
       with:
         node-version: 20
         cache: 'npm'