Update urllib3 to 1.25.9

[pyup-bot]

This PR updates urllib3 from 1.25.7 to 1.25.9.

Changelog

1.25.9

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

* Added ``InvalidProxyConfigurationWarning`` which is raised when
erroneously specifying an HTTPS proxy URL. urllib3 doesn't currently
support connecting to HTTPS proxies but will soon be able to
and we would like users to migrate properly without much breakage.

See `this GitHub issue <https://github.com/urllib3/urllib3/issues/1850>`_
for more information on how to fix your proxy config. (Pull 1851)

* Drain connection after ``PoolManager`` redirect (Pull 1817)

* Ensure ``load_verify_locations`` raises ``SSLError`` for all backends (Pull 1812)

* Rename ``VerifiedHTTPSConnection`` to ``HTTPSConnection`` (Pull 1805)

* Allow the CA certificate data to be passed as a string (Pull 1804)

* Raise ``ValueError`` if method contains control characters (Pull 1800)

* Add ``__repr__`` to ``Timeout`` (Pull 1795)

1.25.8

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

* Drop support for EOL Python 3.4 (Pull 1774)

* Optimize _encode_invalid_chars (Pull 1787)

Links

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

[pyup-bot]

Closing this in favor of #254