Merge pull request #3548 from blueyed/fix-docs

tox: clean up docs target

Author: blueyed

tox.ini

@@ -115,8 +115,6 @@ skipsdist = True
 usedevelop = True
 changedir = doc/en
 deps =
-    attrs
-    more-itertools
     PyYAML
     sphinx
     sphinxcontrib-trio