Update urllib3 to 1.23

[pyup-bot]

This PR updates urllib3 from 1.22 to 1.23.

Changelog

1.23

-----------------

* Allow providing a list of headers to strip from requests when redirecting
to a different host. Defaults to the ``Authorization`` header. Different
headers can be set via ``Retry.remove_headers_on_redirect``. (Issue 1316)

* Fix ``util.selectors._fileobj_to_fd`` to accept ``long`` (Issue 1247).

* Dropped Python 3.3 support. (Pull 1242)

* Put the connection back in the pool when calling stream() or read_chunked() on
a chunked HEAD response. (Issue 1234)

* Fixed pyOpenSSL-specific ssl client authentication issue when clients
attempted to auth via certificate + chain (Issue 1060)

* Add the port to the connectionpool connect print (Pull 1251)

* Don't use the ``uuid`` module to create multipart data boundaries. (Pull 1380)

* ``read_chunked()`` on a closed response returns no chunks. (Issue 1088)

* Add Python 2.6 support to ``contrib.securetransport`` (Pull 1359)

* Added support for auth info in url for SOCKS proxy (Pull 1363)

Links

• PyPI: https://pypi.org/project/urllib3
• Changelog: https://pyup.io/changelogs/urllib3/
• Docs: https://urllib3.readthedocs.io/

[coveralls]

Pull Request Test Coverage Report for Build 21

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 48.615%

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Totals
Change from base Build 18:	0.0%
Covered Lines:	351
Relevant Lines:	722

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💛 - Coveralls