Bump coverage from 6.4.1 to 6.4.3

Bumps [coverage](https://github.com/nedbat/coveragepy) from 6.4.1 to 6.4.3.
- [Release notes](https://github.com/nedbat/coveragepy/releases)
- [Changelog](https://github.com/nedbat/coveragepy/blob/master/CHANGES.rst)
- [Commits](nedbat/coveragepy@6.4.1...6.4.3)

---
updated-dependencies:
- dependency-name: coverage
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

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

requirements-dev.txt

@@ -5,7 +5,7 @@ isort==5.10.1
 flake8==4.0.1
 pydocstyle==6.1.1
 docformatter==1.4
-coverage==6.4.1
+coverage==6.4.3
 autoflake==1.4
 tox==3.25.1
 pur==7.0.0