Bump karma-coveralls from 1.1.2 to 2.1.0

Bumps [karma-coveralls](https://github.com/caitp/karma-coveralls) from 1.1.2 to 2.1.0.
- [Release notes](https://github.com/caitp/karma-coveralls/releases)
- [Commits](https://github.com/caitp/karma-coveralls/commits)

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

Author: dependabot[bot]