Bump actions/setup-node from 5 to 6

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>

Author: dependabot[bot]

.github/workflows/e2e-test.yml

@@ -188,7 +188,7 @@ jobs:
           repository: ether/etherpad-lite
           path: etherpad
           ref: 1.7.0
-      - uses: actions/setup-node@v5
+      - uses: actions/setup-node@v6
         with:
           node-version: "8.9"
       - uses: JarvusInnovations/background-action@v1
@@ -235,7 +235,7 @@ jobs:
       with:
         repository: ether/etherpad-lite
         path: etherpad
-    - uses: actions/setup-node@v5
+    - uses: actions/setup-node@v6
       with:
         node-version: 20
     - uses: JarvusInnovations/background-action@v1