build(deps-dev): bump coverage from 5.3.1 to 5.4

Bumps [coverage](https://github.com/nedbat/coveragepy) from 5.3.1 to 5.4.
- [Release notes](https://github.com/nedbat/coveragepy/releases)
- [Changelog](https://github.com/nedbat/coveragepy/blob/master/CHANGES.rst)
- [Commits](nedbat/coveragepy@coverage-5.3.1...coverage-5.4)

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