Update mysqlclient to 1.4.3

[pyup-bot]

This PR updates mysqlclient from 1.4.2.post1 to 1.4.3.

Changelog

1.4.3

======================

Release: 2019-08-09

* ``--static`` build supports ``libmariadbclient.a``
* Try ``mariadb_config`` when ``mysql_config`` is not found
* Fixed warning happend in Python 3.8 (359)
* Fixed ``from MySQLdb import *``, while I don't recommend it. (369)
* Fixed SEGV ``MySQLdb.escape_string("1")`` when libmariadb is used and
no connection is created. (367)
* Fixed many circular references are created in ``Cursor.executemany()``. (375)


======================

Links

• PyPI: https://pypi.org/project/mysqlclient
• Changelog: https://pyup.io/changelogs/mysqlclient/
• Repo: https://github.com/PyMySQL/mysqlclient-python

[coveralls]

Pull Request Test Coverage Report for Build 3649

• 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 73.683%

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Totals
Change from base Build 3643:	0.0%
Covered Lines:	3693
Relevant Lines:	4752

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💛 - Coveralls