composer: require ecs locally

Author: TomasVotruba

composer.json

@@ -19,7 +19,8 @@
         "mockery/mockery": "^1.0",
         "phpunit/phpunit": "^6.4",
         "doctrine/instantiator": "^1.0",
-        "phpstan/phpstan": "^0.9.0"
+        "phpstan/phpstan": "^0.9.0",
+        "symplify/easy-coding-standard": "^3.0"
     },
     "autoload": {
         "psr-4": {