Update sabre/dav requirement from 4.2.1 to 4.2.3 in /build/integration
Updates the requirements on [sabre/dav](https://github.com/sabre-io/dav) to permit the latest version.
- [Release notes](https://github.com/sabre-io/dav/releases)
- [Changelog](https://github.com/sabre-io/dav/blob/master/CHANGELOG.md)
- [Commits](https://github.com/sabre-io/dav/compare/4.2.1...4.2.3)