Bump sphinx from 3.0.3 to 3.0.4 (#859)

Bumps [sphinx](https://github.com/sphinx-doc/sphinx) from 3.0.3 to 3.0.4.
- [Release notes](https://github.com/sphinx-doc/sphinx/releases)
- [Changelog](https://github.com/sphinx-doc/sphinx/blob/3.x/CHANGES)
- [Commits](sphinx-doc/sphinx@v3.0.3...v3.0.4)

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

@@ -1,2 +1,2 @@
-sphinx==3.0.3
+sphinx==3.0.4
 sphinx-autodoc-typehints==1.8.0