Bump coverage from 4.5.3 to 4.5.4

Bumps [coverage](https://github.com/nedbat/coveragepy) from 4.5.3 to 4.5.4.
- [Release notes](https://github.com/nedbat/coveragepy/releases)
- [Changelog](https://github.com/nedbat/coveragepy/blob/master/CHANGES.rst)
- [Commits](nedbat/coveragepy@coverage-4.5.3...coverage-4.5.4)

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

requirements.txt

@@ -1,5 +1,5 @@
 bandit==1.6.2
-coverage==4.5.3
+coverage==4.5.4
 coveralls==1.8.1
 docutils==0.14
 Flask==1.1.1