Update coverage to 4.5.4

[pyup-bot]

This PR updates coverage from 4.5.2 to 4.5.4.

Changelog

4.5.4

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

- Multiprocessing support in Python 3.8 was broken, but is now fixed.  Closes
`issue 828`_.

.. _issue 828: https://github.com/nedbat/coveragepy/issues/828


.. _changes_453:

4.5.3

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

- Only packaging metadata changes.


.. _changes_452:

Links

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

[codecov]

Codecov Report

Merging #133 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #133   +/-   ##
=======================================
  Coverage   98.85%   98.85%           
=======================================
  Files          35       35           
  Lines         522      522           
=======================================
  Hits          516      516           
  Misses          6        6

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[pyup-bot]

Closing this in favor of #175