Update guzzlehttp/guzzle requirement in /build/integration
Updates the requirements on [guzzlehttp/guzzle](https://github.com/guzzle/guzzle) to permit the latest version.
- [Release notes](https://github.com/guzzle/guzzle/releases)
- [Changelog](https://github.com/guzzle/guzzle/blob/master/CHANGELOG.md)
- [Commits](https://github.com/guzzle/guzzle/compare/7.4.1...7.4.2)