Update coverage to 5.2.1

[pyup-bot]

This PR updates coverage from 5.2 to 5.2.1.

Changelog

5.2.1

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

- The dark mode HTML report still used light colors for the context listing,
making them unreadable (`issue 1009`_).  This is now fixed.

- The time stamp on the HTML report now includes the time zone. Thanks, Xie
Yanbo (`pull request 960`_).

.. _pull request 960: https://github.com/nedbat/coveragepy/pull/960
.. _issue 1009: https://github.com/nedbat/coveragepy/issues/1009


.. _changes_52:

Links

• PyPI: https://pypi.org/project/coverage
• Changelog: https://pyup.io/changelogs/coverage/
• Repo: https://github.com/nedbat/coveragepy

[pyup-bot]

Closing this in favor of #184