remove PHP require version. We support all versions that magento supoprt.

composer.json

@@ -8,7 +8,6 @@
     "AFL-3.0"
   ],
   "require": {
-    "php": "~5.5.0|~5.6.0|~7.0.0",
     "adyen/php-api-library": "*"
   },
   "autoload": {