chore(deps): update actions/setup-node action to v6

Author: renovate[bot]

.github/workflows/sync-index.yml

@@ -23,7 +23,7 @@ jobs:
         uses: actions/checkout@v5
 
       - name: Setup Node.js
-        uses: actions/setup-node@v5
+        uses: actions/setup-node@v6
         with:
           node-version: '22'
 

.github/workflows/verify-build.yml

@@ -17,7 +17,7 @@ jobs:
         uses: actions/checkout@v5
 
       - name: Setup Node.js
-        uses: actions/setup-node@v5
+        uses: actions/setup-node@v6
         with:
           node-version: '22'