Bump sphinx-autoapi from 3.1.1 to 3.2.0 in /docs/source

Bumps [sphinx-autoapi](https://github.com/readthedocs/sphinx-autoapi) from 3.1.1 to 3.2.0.
- [Release notes](https://github.com/readthedocs/sphinx-autoapi/releases)
- [Changelog](https://github.com/readthedocs/sphinx-autoapi/blob/main/CHANGELOG.rst)
- [Commits](readthedocs/sphinx-autoapi@v3.1.1...v3.2.0)

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

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

docs/source/requirements.txt

@@ -1,2 +1,2 @@
 sphinx==7.3.7
-sphinx-autoapi==3.1.1
+sphinx-autoapi==3.2.0