Update sphinx from 1.8.4 to 1.8.5 (#594)

Author: pyup-bot

requirements-development.txt

@@ -13,6 +13,6 @@ pytest-cov==2.6.1
 pytest-django==3.4.8
 pytest-factoryboy==2.0.2
 recommonmark==0.5.0
-Sphinx==1.8.4
+Sphinx==1.8.5
 sphinx_rtd_theme==0.4.3
 twine==1.13.0