build(deps): bump sphinx from 2.3.1 to 3.0.2 (#672)

Bumps [sphinx](https://github.com/sphinx-doc/sphinx) from 2.3.1 to 3.0.2.
- [Release notes](https://github.com/sphinx-doc/sphinx/releases)
- [Changelog](https://github.com/sphinx-doc/sphinx/blob/3.x/CHANGES)
- [Commits](sphinx-doc/sphinx@v2.3.1...v3.0.2)

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

Co-authored-by: dependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>

docs-requirements.txt

@@ -1,4 +1,4 @@
-sphinx==2.3.1
+sphinx==3.0.2
 sphinx-rtd-theme
 sphinx-autodoc-typehints[type_comments]>=1.8.0
 typing-extensions