Bump coveralls from 2.2.0 to 3.1.0

Bumps [coveralls](https://github.com/TheKevJames/coveralls-python) from 2.2.0 to 3.1.0.
- [Release notes](https://github.com/TheKevJames/coveralls-python/releases)
- [Changelog](https://github.com/TheKevJames/coveralls-python/blob/master/CHANGELOG.md)
- [Commits](TheKevJames/coveralls-python@2.2.0...3.1.0)

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

Author: dependabot-preview[bot]