Update actions/setup-node action to v6

Author: renovate[bot]

.github/workflows/continuous-integration.yml

@@ -16,7 +16,7 @@ jobs:
                   timezone: Europe/Berlin
             - uses: actions/checkout@v4
             - name: Use Node.js v${{ matrix.node-version }}
-              uses: actions/setup-node@v4
+              uses: actions/setup-node@v6
               with:
                   node-version: ${{ matrix.node-version }}
             - name: Install dependencies