Bump sphinx from 3.1.2 to 3.2.1

Bumps [sphinx](https://github.com/sphinx-doc/sphinx) from 3.1.2 to 3.2.1.
- [Release notes](https://github.com/sphinx-doc/sphinx/releases)
- [Changelog](https://github.com/sphinx-doc/sphinx/blob/3.x/CHANGES)
- [Commits](sphinx-doc/sphinx@v3.1.2...v3.2.1)

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

Author: dependabot-preview[bot]

poetry.lock

@@ -28,7 +28,7 @@ pytest-cov = "^2.10.0"
 numpy = "^1.19.1"
 jsonschema = "^3.2.0"
 pylint = "^2.5.3"
-sphinx = "^3.1.2"
+sphinx = "^3.2.1"
 sphinx-autoapi = "^1.4.0"
 sphinx-rtd-theme = "^0.5.0"