Update sabre/dav requirement from 4.2.3 to 4.3.0 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/4.2.3...4.3.0)

---
updated-dependencies:
- dependency-name: sabre/dav
  dependency-type: direct:development
...

Signed-off-by: dependabot[bot] <support@github.com>

build/integration/composer.json

@@ -4,7 +4,7 @@
     "behat/behat": "~3.10.0",
     "guzzlehttp/guzzle": "6.5.5",
     "jarnaiz/behat-junit-formatter": "^1.3",
-    "sabre/dav": "4.2.3",
+    "sabre/dav": "4.3.0",
     "symfony/event-dispatcher": "~4.4"
   }
 }