fix(php): add support for php 5.6 and 7.1

Author: sudkumar

composer.json

@@ -24,7 +24,7 @@
         "email": "[email protected]"
     },
     "require": {
-        "php": ">=7.1",
+        "php": "^5.6|^7.1",
         "craftsys/msg91-php": "^0.8",
         "illuminate/support": "^5.2|^6.0|^7.0"
     },