Bump actions/setup-node from 2 to 6

Bumps [actions/setup-node](https://github.com/actions/setup-node) from 2 to 6.
- [Release notes](https://github.com/actions/setup-node/releases)
- [Commits](actions/setup-node@v2...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>

Author: dependabot[bot]

.github/workflows/ci.yml

@@ -19,7 +19,7 @@ jobs:
         uses: actions/checkout@v4
 
       - name: Set up Node.js
-        uses: actions/setup-node@v4
+        uses: actions/setup-node@v6
         with:
           node-version: 24
           cache: npm

.github/workflows/nextrelease.yml

@@ -14,7 +14,7 @@ jobs:
     - uses: actions/checkout@v2
       with:
         fetch-depth: 0
-    - uses: actions/setup-node@v2
+    - uses: actions/setup-node@v6
       with:
         node-version: 'lts/*'
     - uses: dropseed/nextrelease@v1