Update actions/setup-node action to v6

| datasource  | package            | from | to |
| ----------- | ------------------ | ---- | -- |
| github-tags | actions/setup-node | v5   | v6 |

Author: renovate[bot]

.github/workflows/ci.yml

@@ -12,7 +12,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v5
-      - uses: actions/setup-node@v5
+      - uses: actions/setup-node@v6
         with:
           node-version-file: '.nvmrc'
           cache: 'npm'