tox: do not force py34 with check/clean/…

Author: blueyed

tox.ini

@@ -16,7 +16,6 @@ basepython =
     py35: {env:TOXPYTHON:python3.5}
     py36: {env:TOXPYTHON:python3.6}
     py37: {env:TOXPYTHON:python3.7}
-    {clean,check,report,extension-coveralls,coveralls,spell}: python3.4
 setenv =
     PYTHONPATH={toxinidir}/tests
     PYTHONUNBUFFERED=yes