set required php version to 7.2

Author: SaadEddin A. Hassania

composer.json

@@ -23,7 +23,7 @@
     }
   ],
   "require": {
-    "php": ">=5.4.0",
+    "php": ">=7.2.0",
     "ext-exif": "*",
     "ext-fileinfo": "*",
     "intervention/image": "2.*",