Update symfony/event-dispatcher requirement in /build/integration

Updates the requirements on [symfony/event-dispatcher](https://github.com/symfony/event-dispatcher) to permit the latest version.
- [Release notes](https://github.com/symfony/event-dispatcher/releases)
- [Changelog](https://github.com/symfony/event-dispatcher/blob/5.3/CHANGELOG.md)
- [Commits](https://github.com/symfony/event-dispatcher/compare/v4.4.0...v5.3.0)

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

build/integration/composer.json

@@ -5,6 +5,6 @@
     "guzzlehttp/guzzle": "6.5.2",
     "jarnaiz/behat-junit-formatter": "^1.3",
     "sabre/dav": "3.2.3",
-    "symfony/event-dispatcher": "~4.4"
+    "symfony/event-dispatcher": "~5.3"
   }
 }