⬆️ Bump coverage from 5.3 to 5.3.1 (#220)

Bumps [coverage](https://github.com/nedbat/coveragepy) from 5.3 to 5.3.1.
- [Release notes](https://github.com/nedbat/coveragepy/releases)
- [Changelog](https://github.com/nedbat/coveragepy/blob/master/CHANGES.rst)
- [Commits](nedbat/coveragepy@coverage-5.3...coverage-5.3.1)

Signed-off-by: dependabot[bot] <support@github.com>

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

requirements_test.txt

@@ -1,5 +1,5 @@
 aresponses==2.0.0
-coverage==5.3
+coverage==5.3.1
 flake8==3.8.4
 flake8-docstrings==1.5.0
 isort==5.6.4