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

Author: renovate[bot]

.github/workflows/ci.yml

@@ -12,7 +12,7 @@ jobs:
     # Setup.
     - uses: actions/checkout@v4
     - name: Use Node.js ${{ matrix.node-version }}
-      uses: actions/setup-node@v4
+      uses: actions/setup-node@v6
       with:
         node-version: ${{ matrix.node-version }}
     - run: corepack enable