Bump coverage from 7.6.1 to 7.6.9

Bumps [coverage](https://github.com/nedbat/coveragepy) from 7.6.1 to 7.6.9.
- [Release notes](https://github.com/nedbat/coveragepy/releases)
- [Changelog](https://github.com/nedbat/coveragepy/blob/master/CHANGES.rst)
- [Commits](https://github.com/nedbat/coveragepy/compare/7.6.1...7.6.9)

Changelog: chore