Bump actions/upload-pages-artifact from 3 to 4 (#12922)

Bumps [actions/upload-pages-artifact](https://github.com/actions/upload-pages-artifact) from 3 to 4.
- [Release notes](https://github.com/actions/upload-pages-artifact/releases)
- [Commits](https://github.com/actions/upload-pages-artifact/compare/v3...v4)

---
updated-dependencies:
- dependency-name: actions/upload-pages-artifact
  dependency-version: '4'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

.github/workflows/sphinx.yml

@@ -34,7 +34,7 @@ jobs:
       - run: uv sync --group=docs
       - uses: actions/configure-pages@v5
       - run: uv run sphinx-build -c docs . docs/_build/html
-      - uses: actions/upload-pages-artifact@v3
+      - uses: actions/upload-pages-artifact@v4
         with:
           path: docs/_build/html