Bump sphinx-autobuild from 2021.3.14 to 2024.9.3

Bumps [sphinx-autobuild](https://github.com/sphinx-doc/sphinx-autobuild) from 2021.3.14 to 2024.9.3.
- [Release notes](https://github.com/sphinx-doc/sphinx-autobuild/releases)
- [Changelog](https://github.com/sphinx-doc/sphinx-autobuild/blob/main/NEWS.rst)
- [Commits](sphinx-doc/sphinx-autobuild@2021.03.14...2024.09.03)

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

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

requirements/docs-auto.txt

@@ -1 +1 @@
-sphinx-autobuild==2021.3.14
+sphinx-autobuild==2024.9.3