⬆️ Update sphinx requirement

Updates the requirements on [sphinx](https://github.com/sphinx-doc/sphinx) to permit the latest version.
- [Release notes](https://github.com/sphinx-doc/sphinx/releases)
- [Changelog](https://github.com/sphinx-doc/sphinx/blob/master/CHANGES)
- [Commits](sphinx-doc/sphinx@v5.3.0...v6.1.3)

---
updated-dependencies:
- dependency-name: sphinx
  dependency-type: direct:production
...

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

pyproject.toml

@@ -59,7 +59,7 @@ tests = [
     "pytest-cov>=3.0.0,<3.0.1",
 ]
 docs = [
-    "sphinx>=5.3.0,<5.4.0",
+    "sphinx>=5.3.0,<6.2.0",
     "furo==2022.12.7",
     "sphinx-copybutton>=0.5.1,<0.5.2",
     "sphinxext-opengraph>=0.7.3,<0.7.4",