chore: remove php version

Author: xchopin

composer.json

@@ -13,11 +13,9 @@
     }
   ],
   "require": {
-    "php":                           "^5.5",
     "guzzlehttp/guzzle":             "^6.3.3"
   },
   "require-dev": {
-    "php":                           "^7.0.0",
     "phpunit/phpunit": "^7"
   },
   "config": {