python: dataclasses: 0.5 -> 0.6

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

···
 
 buildPythonPackage rec {
   pname = "dataclasses";
-  version = "0.5";
+  version = "0.6";
 
   # backport only works on Python 3.6, and is in the standard library in Python 3.7
   disabled = !isPy36;
 
   src = fetchPypi {
     inherit pname version;
-    sha256 = "07lgn1k56sqpw7yfzv5a6mwshsgaipjawflgyr6lrkryjl64481z";
+    sha256 = "6988bd2b895eef432d562370bb707d540f32f7360ab13da45340101bc2307d84";
   };
 
   meta = with stdenv.lib; {