Update composer.json

Author: mpdude

composer.json

@@ -19,6 +19,7 @@
   ],
 
   "require": {
+    "php": "^7.1",
     "symfony/config": "^2.8 || ^3.0 || ^4.0",
     "symfony/dependency-injection": "^2.8 || ^3.0 || ^4.0",
     "symfony/http-foundation": "^2.8 || ^3.0 || ^4.0",