Bump sphinx from 1.8.2 to 1.8.3

Bumps [sphinx](https://github.com/sphinx-doc/sphinx) from 1.8.2 to 1.8.3.
- [Release notes](https://github.com/sphinx-doc/sphinx/releases)
- [Changelog](https://github.com/sphinx-doc/sphinx/blob/master/CHANGES)
- [Commits](sphinx-doc/sphinx@v1.8.2...v1.8.3)

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

Author: dependabot-support

docs/requirements.txt

@@ -1,4 +1,4 @@
 
-sphinx==1.8.2
+sphinx==1.8.3
 PyYAML==3.13
 sphinx-issues==1.1.0