build(deps): bump crazy-max/ghaction-github-pages from 2 to 4

Bumps [crazy-max/ghaction-github-pages](https://github.com/crazy-max/ghaction-github-pages) from 2 to 4.
- [Release notes](https://github.com/crazy-max/ghaction-github-pages/releases)
- [Commits](https://github.com/crazy-max/ghaction-github-pages/compare/v2...v4)

---
updated-dependencies:
- dependency-name: crazy-max/ghaction-github-pages
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

.github/workflows/doc.yaml

@@ -20,7 +20,7 @@ jobs:
             access-tokens = github.com=${{ secrets.GITHUB_TOKEN }}
       - run: nix build .#nixpkgs-update-doc
       - if: success()
-        uses: crazy-max/ghaction-github-pages@v2
+        uses: crazy-max/ghaction-github-pages@v4
         with:
           target_branch: gh-pages
           build_dir: result/multi