Bump sphinx from 2.2.2 to 2.3.0 (#211)

Bumps [sphinx](https://github.com/sphinx-doc/sphinx) from 2.2.2 to 2.3.0.
- [Release notes](https://github.com/sphinx-doc/sphinx/releases)
- [Changelog](https://github.com/sphinx-doc/sphinx/blob/master/CHANGES)
- [Commits](sphinx-doc/sphinx@v2.2.2...v2.3.0)

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

Author: dependabot-preview[bot]

poetry.lock

@@ -62,7 +62,7 @@ pytest-randomly = "^3.1"
 pytest-asyncio = "^0.10.0"
 pytest-mypy-plugins = "^1.1"
 
-sphinx = "^2.2"
+sphinx = "^2.3"
 sphinx-autodoc-typehints = "^1.10"
 sphinxcontrib-mermaid = "^0.3.1"
 sphinx-typlog-theme = "^0.8.0"