Upgraded required Symfony version

Geolim4 · Geolim4 · commit 8c2ba49ecdc6 · 2016-12-07T19:21:52.000+01:00
diff --git a/composer.json b/composer.json
@@ -28,7 +28,7 @@
         ],
     "require": {
         "php": "^5.6 || ^7.0",
-        "symfony/symfony": "^3.0",
+        "symfony/symfony": "^3.1",
         "phpFastCache/phpFastCache": "^6.0"
     },
     "autoload": {
