Update composer.json

Author: bigrocs

composer.json

@@ -20,7 +20,7 @@
     ],
     "require": {
         "php": "~5.6|~7.0",
-        "symfony/event-dispatcher": "^2.8",
+        "symfony/event-dispatcher": "2.8.27",
         "CoreCMF/admin": "1.1.*",
         "CoreCMF/core": "1.1.*",
         "illuminate/support": "~5.1"