build(deps): bump crazy-max/ghaction-github-pages from 3 to 4

Bumps [crazy-max/ghaction-github-pages](https://github.com/crazy-max/ghaction-github-pages) from 3 to 4.
- [Release notes](https://github.com/crazy-max/ghaction-github-pages/releases)
- [Commits](crazy-max/ghaction-github-pages@v3...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/nix.yml

@@ -61,7 +61,7 @@ jobs:
           cp -r "$(readlink ./result)" book
       - name: Deploy to GitHub Pages
         if: github.ref == 'refs/heads/main'
-        uses: crazy-max/ghaction-github-pages@v3
+        uses: crazy-max/ghaction-github-pages@v4
         with:
           target_branch: gh-pages
           build_dir: book