Upgrade to Symfony 4

Author: theofidry

composer.json

@@ -25,10 +25,10 @@
         "pimple/pimple": "^3.1.0",
         "psr/container": "^1.0.0",
         "rdlowrey/auryn": "^1.4.0",
-        "symfony/config": "3.4.x-dev",
-        "symfony/dependency-injection": "3.4.x-dev",
-        "symfony/filesystem": "3.4.x-dev",
-        "symfony/process": "3.4.x-dev",
+        "symfony/config": "^4.0",
+        "symfony/dependency-injection": "^4.0",
+        "symfony/filesystem": "^4.0",
+        "symfony/process": "^4.0",
         "thecodingmachine/yaco": "^1.0.0",
         "yiisoft/yii2": "^2.0.11",
         "woohoolabs/zen": "^2.0.0",