Bump sphinx from 1.8.4 to 1.8.5 in /docs

Bumps [sphinx](https://github.com/sphinx-doc/sphinx) from 1.8.4 to 1.8.5.
- [Release notes](https://github.com/sphinx-doc/sphinx/releases)
- [Changelog](https://github.com/sphinx-doc/sphinx/blob/master/CHANGES)
- [Commits](sphinx-doc/sphinx@v1.8.4...v1.8.5)

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

Author: dependabot-support

docs/requirements.txt

@@ -1,7 +1,7 @@
 # This file is used to setup env
 # to generate documentation.
 
-sphinx==1.8.4
+sphinx==1.8.5
 sphinx_autodoc_typehints==1.6.0
 sphinxcontrib-mermaid==0.3.1
 sphinx-typlog-theme==0.7.2