Bump capybara from 2.17.0 to 2.18.0
Bump capybara from 2.17.0 to 2.18.0

Bumps [capybara](https://github.com/teamcapybara/capybara) from 2.17.0 to 2.18.0.
- [Changelog](https://github.com/teamcapybara/capybara/blob/master/History.md)
- [Commits](https://github.com/teamcapybara/capybara/compare/2.17.0...2.18.0)
ministryofjustice/prison-visits-2,ministryofjustice/prison-visits-2,ministryofjustice/prison-visits-2,ministryofjustice/prison-visits-2