revert changes to python_environments.py

Author: dojutsu-user

readthedocs/doc_builder/python_environments.py

@@ -325,8 +325,7 @@ def install_core_requirements(self):
                     negative='sphinx<2',
                 ),
                 'sphinx-rtd-theme<0.5',
-                # 'readthedocs-sphinx-ext<0.7',
-                'git+https://github.com/readthedocs/readthedocs-sphinx-ext@master',
+                'readthedocs-sphinx-ext<0.7',
             ])
 
         cmd = copy.copy(pip_install_cmd)