Bump actions/setup-node from 5 to 6 (#3915)

Bumps [actions/setup-node](https://github.com/actions/setup-node) from 5 to 6.
- [Release notes](https://github.com/actions/setup-node/releases)
- [Commits](actions/setup-node@v5...v6)

---
updated-dependencies:
- dependency-name: actions/setup-node
  dependency-version: '6'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

.github/workflows/ci.yml

@@ -1398,7 +1398,7 @@ jobs:
     - uses: VirtusLab/scala-cli-setup@v1
       with:
         jvm: "zulu:17"
-    - uses: actions/setup-node@v5
+    - uses: actions/setup-node@v6
       with:
         node-version: 24
     - name: Build documentation

.github/workflows/website.yaml

@@ -12,7 +12,7 @@ jobs:
       with:
         fetch-depth: 0
         submodules: true
-    - uses: actions/setup-node@v5
+    - uses: actions/setup-node@v6
       with:
         node-version: 18
     - run: .github/scripts/update-website.sh