Merge pull request #286797 from seb314/seb314/fix-piep-py3

python3Packages.piep: fix enable for python3

pkgs/development/python-modules/piep/default.nix

···
   version = "0.10.0";
   format = "setuptools";
   pname = "piep";
-  disabled = isPy3k;
+  disabled = !isPy3k;
 
   src = fetchPypi {
     inherit pname version;