Bump coverage from 6.3.3 to 6.4.1

Bumps [coverage](https://github.com/nedbat/coveragepy) from 6.3.3 to 6.4.1.
- [Release notes](https://github.com/nedbat/coveragepy/releases)
- [Changelog](https://github.com/nedbat/coveragepy/blob/master/CHANGES.rst)
- [Commits](nedbat/coveragepy@6.3.3...6.4.1)

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

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

Author: dependabot[bot]

docs/requirements.txt

@@ -10,7 +10,7 @@ cffi==1.15.0; python_version >= "3.6"
 charset-normalizer==2.0.12; python_version >= "3.7" and python_version < "4" and python_full_version >= "3.6.0"
 click==8.1.3; python_version >= "3.7" and python_full_version >= "3.6.2"
 colorama==0.4.4; sys_platform == "win32" and python_version >= "3.7" and python_full_version >= "3.6.2" and (python_version >= "3.6" and python_full_version < "3.0.0" or python_full_version >= "3.4.0" and python_version >= "3.6") and platform_system == "Windows"
-coverage==6.3.3; python_version >= "3.7"
+coverage==6.4.1; python_version >= "3.7"
 decorator==5.1.1; python_version >= "3.5"
 docutils==0.17.1; python_version >= "3.6" and python_full_version < "3.0.0" or python_full_version >= "3.5.0" and python_version >= "3.6"
 execnet==1.9.0; python_version >= "3.6" and python_full_version < "3.0.0" or python_full_version >= "3.5.0" and python_version >= "3.6"