Merge pull request #5789 from rtfd/bump-sphinx-ext

Fix version of our sphinx-ext we're installing

Author: ericholscher

readthedocs/doc_builder/python_environments.py

@@ -325,7 +325,7 @@ def install_core_requirements(self):
                     negative='sphinx<2',
                 ),
                 'sphinx-rtd-theme<0.5',
-                'readthedocs-sphinx-ext<0.6',
+                'readthedocs-sphinx-ext<0.7',
             ])
 
         cmd = copy.copy(pip_install_cmd)