Upgrade all CI to Sphinx 1.8.5

Author: wouterj

_build/.requirements.txt

@@ -9,5 +9,5 @@ pytz==2017.2
 requests==2.20.0
 six==1.10.0
 snowballstemmer==1.2.1
-sphinx==1.3.6
+sphinx==1.8.5
 git+https://github.com/fabpot/sphinx-php.git@v1.0.14#egg_name=sphinx-php