Update zendframework/zend-diactoros requirement from ^1.8.6 to ^2.2.1

Updates the requirements on [zendframework/zend-diactoros](https://github.com/zendframework/zend-diactoros) to permit the latest version.
- [Release notes](https://github.com/zendframework/zend-diactoros/releases)
- [Changelog](https://github.com/zendframework/zend-diactoros/blob/master/CHANGELOG.md)
- [Commits](zendframework/zend-diactoros@1.8.6...2.2.1)

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

composer.json

@@ -26,7 +26,7 @@
     "doctrine/cache": "^1.8",
     "symfony/psr-http-message-bridge": "^1",
     "nyholm/psr7": "^1.1",
-    "zendframework/zend-diactoros": "^1.8.6",
+    "zendframework/zend-diactoros": "^2.2.1",
     "overblog/graphiql-bundle": "^0.1.2 | ^0.2",
     "thecodingmachine/cache-utils": "^1"
   },