Bump coveralls from 1.8.2 to 1.9.1 (#855)
Bump coveralls from 1.8.2 to 1.9.1 (#855)

Bumps [coveralls](https://github.com/coveralls-clients/coveralls-python) from 1.8.2 to 1.9.1.
- [Release notes](https://github.com/coveralls-clients/coveralls-python/releases)
- [Changelog](https://github.com/coveralls-clients/coveralls-python/blob/master/CHANGELOG.md)
- [Commits](https://github.com/coveralls-clients/coveralls-python/compare/1.8.2...1.9.1)

Signed-off-by: dependabot-preview[bot] <5bdcd3c0d4d24ae3e71b3b452a024c6324c7e4bb@dependabot.com>
mozilla/bztools,mozilla/relman-auto-nag,mozilla/relman-auto-nag,mozilla/relman-auto-nag