chore: update actions/checkout action to v6

Author: renovate[bot]

.github/workflows/CI.yml

@@ -13,7 +13,7 @@ jobs:
 
     steps:
       - name: Checkout
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
       - name: Use Node.js
         uses: actions/setup-node@v6
         with: