Add Support to php 8 (#20)

Co-authored-by: vagrant <vagrant@homestead>

Author: owenbanan-cp

composer.json

@@ -16,15 +16,15 @@
         }
     ],
     "require": {
-        "php": "^7.2",
+        "php": "^7.2|^8.0",
         "ext-json": "*",
         "guzzlehttp/guzzle": "^6.0 || ^7.0",
         "nesbot/carbon": "^2.0"
     },
     "require-dev": {
+        "dms/phpunit-arraysubset-asserts": "^0.4.0",
         "mockery/mockery": "^1.3",
         "phpunit/phpunit": "^8.2",
-        "dms/phpunit-arraysubset-asserts": "^0.1.0",
         "symfony/var-dumper": "^4.3"
     },
     "autoload": {