swiftclient: add setuptools

Traceback (most recent call last):
  File "/nix/store/8qkdlyv2ckrimvi50qvl0anzv66jcp2j-python-swiftclient-3.6.0/bin/.swift-wrapped", line 7, in <module>
    from swiftclient.shell import main
  File "/nix/store/8qkdlyv2ckrimvi50qvl0anzv66jcp2j-python-swiftclient-3.6.0/lib/python3.7/site-packages/swiftclient/__init__.py", line 20, in <module>
    from .client import *  # noqa
  File "/nix/store/8qkdlyv2ckrimvi50qvl0anzv66jcp2j-python-swiftclient-3.6.0/lib/python3.7/site-packages/swiftclient/client.py", line 33, in <module>
    from swiftclient import version as swiftclient_version
  File "/nix/store/8qkdlyv2ckrimvi50qvl0anzv66jcp2j-python-swiftclient-3.6.0/lib/python3.7/site-packages/swiftclient/version.py", line 15, in <module>
    import pkg_resources
ModuleNotFoundError: No module named 'pkg_resources'

pkgs/tools/admin/swiftclient/default.nix

@@ -1,4 +1,4 @@
-{ lib, buildPythonApplication, fetchPypi, requests, six, pbr }:
+{ lib, buildPythonApplication, fetchPypi, requests, six, pbr, setuptools }:
 
 buildPythonApplication rec {
   pname = "python-swiftclient";
@@ -9,7 +9,7 @@ buildPythonApplication rec {
     sha256 = "0sv6z72zdwzwdjng0djk3l2maryn9pz3khf69yq5ig2ycz8hh0qv";
   };
 
-  propagatedBuildInputs = [ requests six pbr ];
+  propagatedBuildInputs = [ requests six pbr setuptools ];
 
   # For the tests the following requirements are needed:
   # https://github.com/openstack/python-swiftclient/blob/master/test-requirements.txt