Use same dependencies for tox -e docs and readthedocs
diff --git a/tox.ini b/tox.ini
index 0465200..0a98945 100644
--- a/tox.ini
+++ b/tox.ini
@@ -65,7 +65,6 @@
 [testenv:docs]
 basepython = python3.5
 deps =
-  {[testenv]deps}
   sphinx
   -r{toxinidir}/docs/requirements-docs.txt
 commands = make -C docs html