Bump sphinx-toolbox from 3.8.0 to 3.9.0

Bumps [sphinx-toolbox](https://github.com/sphinx-toolbox/sphinx-toolbox) from 3.8.0 to 3.9.0.
- [Release notes](https://github.com/sphinx-toolbox/sphinx-toolbox/releases)
- [Changelog](https://github.com/sphinx-toolbox/sphinx-toolbox/blob/master/doc-source/changelog.rst)
- [Commits](sphinx-toolbox/sphinx-toolbox@v3.8.0...v3.9.0)

---
updated-dependencies:
- dependency-name: sphinx-toolbox
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

pyproject.toml

@@ -53,7 +53,7 @@ example = ["gdown==5.2.0"]
 docs = [ "sphinx-mdinclude==0.6.2",
     "sphinx-copybutton==0.5.2",
     "sphinx-tabs==3.4.7",
-    "sphinx-toolbox==3.8.0",
+    "sphinx-toolbox==4.1.2",
     "furo==2024.8.6"]
 dev = ["pre-commit==4.5.1"]