Update coverage requirement from <5.1,>=4.0 to >=4.0,<5.3

Updates the requirements on [coverage](https://github.com/nedbat/coveragepy) to permit the latest version.
- [Release notes](https://github.com/nedbat/coveragepy/releases)
- [Changelog](https://github.com/nedbat/coveragepy/blob/master/CHANGES.rst)
- [Commits](nedbat/coveragepy@coverage-4.0...coverage-5.2)

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

test-requirements.txt

@@ -8,5 +8,5 @@ pytest-cov
 flake8
 coveralls
 codeclimate-test-reporter
-coverage>=4.0,<5.1
+coverage>=4.0,<5.3
 prometheus_client