Bump sphinx from 8.1.0 to 8.1.3

Bumps [sphinx](https://github.com/sphinx-doc/sphinx) from 8.1.0 to 8.1.3.
- [Release notes](https://github.com/sphinx-doc/sphinx/releases)
- [Changelog](https://github.com/sphinx-doc/sphinx/blob/master/CHANGES.rst)
- [Commits](sphinx-doc/sphinx@v8.1.0...v8.1.3)

---
updated-dependencies:
- dependency-name: sphinx
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>

Pipfile

@@ -19,6 +19,6 @@ black = "==24.10.0"
 pytest = "==8.3.3"
 pytest-cov = "==5.0.0"
 tbump = "==6.11.0"
-sphinx = "==8.1.0"
+sphinx = "==8.1.3"
 sphinx-jsonschema = "==1.19.1"
 ruff = "==0.6.9"