revert changes on tox.ini

Author: loechel

tox.ini

@@ -64,7 +64,7 @@ commands =
     check-python-versions
 deps =
     check-manifest
-    check-python-versions >= 0.20.0
+    check-python-versions >= 0.19.1
     wheel
     flake8
     isort
@@ -85,7 +85,6 @@ commands_pre =
 commands =
     sphinx-build -b html -d docs/_build/doctrees docs docs/_build/html
     sphinx-build -b doctest -d docs/_build/doctrees docs docs/_build/doctest
-    coverage run -a -m sphinx -b doctest -d {envdir}/.cache/doctrees docs {envdir}/.cache/doctest
 
 [testenv:coverage]
 basepython = python3.8