Added support for Laravel 5.6

Author: nasrulhazim

composer.json

@@ -23,12 +23,13 @@
         }
     },
     "require": {
-        "illuminate/support": "^5.5",
+        "php": ">=7.1",
+        "illuminate/support": "^5.5|^5.6",
         "moneyphp/money": "^3.1"
     },
     "require-dev": {
-        "phpunit/phpunit": "^6.5",
-        "orchestra/testbench": "~3.0"
+        "phpunit/phpunit": "^6.5|^7.0",
+        "orchestra/testbench": "3.5.*|3.6.*"
     },
     "config": {
         "sort-packages": true