[issue35807] Update bundled pip to 19.0

[Pradyun Gedam]

New submission from Pradyun Gedam <pradyunsg at gmail.com>:

In line with https://bugs.python.org/issue35277.

Will also update setuptools while I do this. (if no one else gets to it, I'll file a PR tomorrow morning)

----------
components: Library (Lib)
messages: 334230
nosy: dstufft, ncoghlan, paul.moore, pradyunsg
priority: normal
severity: normal
status: open
title: Update bundled pip to 19.0

_______________________________________
Python tracker <report at bugs.python.org>
<https://bugs.python.org/issue35807>
_______________________________________