Update actions/setup-node action to v6 (#35)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

.github/workflows/docs-build.yml

@@ -11,7 +11,7 @@ jobs:
       - uses: actions/checkout@v6
 
       - name: Setup Node.js
-        uses: actions/setup-node@v4
+        uses: actions/setup-node@v6
         with:
           node-version: '20'
           cache: 'npm'