change flake8 from using flake8-import-order to using flake8-isort

Author: mattsb42-aws

tox.ini

@@ -192,7 +192,7 @@ basepython = python3
 deps =
     flake8
     flake8-docstrings
-    flake8-import-order
+    flake8-isort
     # https://github.com/JBKahn/flake8-print/pull/30
     flake8-print>=3.1.0
 commands =