[Contracts][EventDispatcher] add EventDispatcherInterface to symfony/contracts and use it where possible

Author: nicolas-grekas

Application.php

@@ -91,6 +91,9 @@ public function __construct(string $name = 'UNKNOWN', string $version = 'UNKNOWN
         $this->defaultCommand = 'list';
     }
 
+    /**
+     * @final since Symfony 4.3, the type-hint will be updated to the interface from symfony/contracts in 5.0
+     */
     public function setDispatcher(EventDispatcherInterface $dispatcher)
     {
         $this->dispatcher = LegacyEventDispatcherProxy::decorate($dispatcher);

composer.json

@@ -17,7 +17,7 @@
     ],
     "require": {
         "php": "^7.1.3",
-        "symfony/contracts": "^1.0",
+        "symfony/contracts": "^1.1",
         "symfony/polyfill-mbstring": "~1.0",
         "symfony/polyfill-php73": "^1.8"
     },