remove -W from sphinx to not treat warning as error

Author: mollyheamazon

tox.ini

@@ -143,7 +143,7 @@ changedir = doc
 # https://github.com/pypa/pip/issues/988
 commands =
     pip install --exists-action=w -r requirements.txt
-    sphinx-build -T -W -b html -d _build/doctrees-readthedocs -D language=en . _build/html
+    sphinx-build -T -b html -d _build/doctrees-readthedocs -D language=en . _build/html
 
 [testenv:doc8]
 deps =