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] <[email protected]>

Author: dependabot[bot]

.github/workflows/js_of_ocaml.yml

@@ -125,7 +125,7 @@ jobs:
           sudo aptitude -o Acquire::Retries=30 install gcc-multilib g++-multilib pkg-config libgmp-dev libgmp-dev:i386 libx11-dev libx11-dev:i386 libxft-dev libxft-dev:i386 -y
 
       - name: Set-up Node.js
-        uses: actions/setup-node@v5
+        uses: actions/setup-node@v6
         with:
           node-version: latest
 

.github/workflows/wasm_of_ocaml.yml

@@ -83,7 +83,7 @@ jobs:
           path: janestreet/opam-repository
 
       - name: Set-up Node.js
-        uses: actions/setup-node@v5
+        uses: actions/setup-node@v6
         with:
           node-version: latest