Bump sphinx from 3.5.1 to 3.5.2 (#286)

Bumps [sphinx](https://github.com/sphinx-doc/sphinx) from 3.5.1 to 3.5.2.
- [Release notes](https://github.com/sphinx-doc/sphinx/releases)
- [Changelog](https://github.com/sphinx-doc/sphinx/blob/3.x/CHANGES)
- [Commits](sphinx-doc/sphinx@v3.5.1...v3.5.2)

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

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]