Bump coverage from 4.5.4 to 5.0

Bumps [coverage](https://github.com/nedbat/coveragepy) from 4.5.4 to 5.0.
- [Release notes](https://github.com/nedbat/coveragepy/releases)
- [Changelog](https://github.com/nedbat/coveragepy/blob/master/CHANGES.rst)
- [Commits](nedbat/coveragepy@coverage-4.5.4...coverage-5.0)

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

requirements-test.txt

@@ -2,7 +2,7 @@
 psutil==5.6.7
 pytest==5.3.2  # tests framework used
 pytest-cov==2.8.1  # coverage reports to verify tests quality
-coverage==4.5.4 # pytest-cov
+coverage==5.0 # pytest-cov
 python-daemon==2.2.4  # used in test for easy creation of daemons
 docutils  # needed for python-daemon
 -e .[tests]