isort: Keep <5

Author: tony

poetry.lock

@@ -15,7 +15,7 @@ python = "~2.7 || ^3.5"
 black = {version="==19.10b0", python="^3.6"}
 docutils = "*"
 flake8 = "*"
-isort = "*"
+isort = "<5"
 pytest = [
   {version="<4.7.0", python="<3"},
   {version="*", python=">=3"}