Bump sphinx from 7.2.6 to 8.2.3

Bumps [sphinx](https://github.com/sphinx-doc/sphinx) from 7.2.6 to 8.2.3.
- [Release notes](https://github.com/sphinx-doc/sphinx/releases)
- [Changelog](https://github.com/sphinx-doc/sphinx/blob/master/CHANGES.rst)
- [Commits](sphinx-doc/sphinx@v7.2.6...v8.2.3)

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

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

Author: dependabot[bot]

pyproject.toml

@@ -13,7 +13,7 @@ dependencies = [
     "matplotlib>=3.10.1",
     "myst-parser[linkify]==2.0.0",
     "shibuya==2025.2.28",
-    "sphinx==7.2.6",
+    "sphinx==8.2.3",
     "sphinx-copybutton==0.5.2",
     "sphinx-design==0.5.0",
     "sphinx-sitemap==2.5.1",