build(deps): bump coverage from 5.5 to 6.0 (#632)

Bumps [coverage](https://github.com/nedbat/coveragepy) from 5.5 to 6.0.
- [Release notes](https://github.com/nedbat/coveragepy/releases)
- [Changelog](https://github.com/nedbat/coveragepy/blob/master/CHANGES.rst)
- [Commits](nedbat/coveragepy@coverage-5.5...6.0)

---
updated-dependencies:
- dependency-name: coverage
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <[email protected]>

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

Author: dependabot[bot]

requirements-test.txt

@@ -5,7 +5,7 @@ black==21.9b0
 codespell==2.1.0
 
 jsonschema==4.0.1
-coverage==5.5
+coverage==6.0
 doc8==0.9.1
 
 types-python-dateutil==2.8.0