py-setuptools: update to 38.1.0.

v38.1.0
-------

* #1208: Improve error message when failing to locate scripts
  in egg-info metadata.

v38.0.0
-------

* #458: In order to support deterministic builds, Setuptools no
  longer allows packages to declare ``install_requires`` as
  unordered sequences (sets or dicts).

v37.0.0
-------

* #878: Drop support for Python 2.6. Python 2.6 users should
  rely on 'setuptools < 37dev'.

v36.8.0
-------

* #1190: In SSL support for package index operations, use SNI
  where available.

v36.7.3
-------

* #1175: Bug fixes to ``build_meta`` module.

(wiz)