Bump sphinx from 2.4.4 to 8.1.3

Bumps [sphinx](https://github.com/sphinx-doc/sphinx) from 2.4.4 to 8.1.3.
- [Release notes](https://github.com/sphinx-doc/sphinx/releases)
- [Changelog](https://github.com/sphinx-doc/sphinx/blob/v8.1.3/CHANGES.rst)
- [Commits](sphinx-doc/sphinx@v2.4.4...v8.1.3)

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

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

doc/requirements.txt

@@ -1,3 +1,3 @@
-sphinx==2.4.4
+sphinx==8.1.3
 sphinx-autodoc-typehints>=1.10.3
 PyQt5>=5.9.0