Bump sentry-raven from 2.6.2 to 2.6.3
Bump sentry-raven from 2.6.2 to 2.6.3

Bumps [sentry-raven](https://github.com/getsentry/raven-ruby) from 2.6.2 to 2.6.3.
- [Release notes](https://github.com/getsentry/raven-ruby/releases/tag/v2.6.3)
- [Changelog](https://github.com/getsentry/raven-ruby/blob/master/changelog.md)
- [Commits](https://github.com/getsentry/raven-ruby/compare/v2.6.2...v2.6.3)
ministryofjustice/prison-visits-2,ministryofjustice/prison-visits-2,ministryofjustice/prison-visits-2,ministryofjustice/prison-visits-2