Bump coverage from 6.2 to 6.3 (#416)

Bumps [coverage](https://github.com/nedbat/coveragepy) from 6.2 to 6.3.
- [Release notes](https://github.com/nedbat/coveragepy/releases)
- [Changelog](https://github.com/nedbat/coveragepy/blob/master/CHANGES.rst)
- [Commits](nedbat/coveragepy@6.2...6.3)

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

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

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

requirements_test.txt

@@ -8,5 +8,5 @@ pre-commit==2.17.0
 flake8-docstrings==1.6.0
 flake8-comprehensions==3.8.0
 flake8-noqa==1.2.1
-coverage==6.2
+coverage==6.3