Bump rollbar from 2.15.2 to 2.15.3
Bump rollbar from 2.15.2 to 2.15.3

Bumps [rollbar](https://github.com/rollbar/rollbar-gem) from 2.15.2 to 2.15.3.
- [Changelog](https://github.com/rollbar/rollbar-gem/blob/master/CHANGELOG.md)
- [Commits](https://github.com/rollbar/rollbar-gem/compare/v2.15.2...v2.15.3)
rdunlop/unicycling-rulebook,rdunlop/unicycling-rulebook,rdunlop/unicycling-rulebook,rdunlop/unicycling-rulebook