Update behat/behat requirement in /build/integration
Updates the requirements on [behat/behat](https://github.com/Behat/Behat) to permit the latest version.
- [Release notes](https://github.com/Behat/Behat/releases)
- [Changelog](https://github.com/Behat/Behat/blob/master/CHANGELOG.md)
- [Commits](https://github.com/Behat/Behat/compare/v3.11.0...v3.12.0)