Added Laravel 7 Support

Author: ssx

composer.json

@@ -10,11 +10,11 @@
         }
     ],
     "require": {
-        "illuminate/contracts": "^5.5|^6.0"
+        "illuminate/contracts": "^5.5|^6.0|^7.0"
     },
     "require-dev": {
-        "orchestra/testbench": "^3.5",
-        "phpunit/phpunit": "^6.0|^7.0"
+        "orchestra/testbench": "^3.5|^5.0",
+        "phpunit/phpunit": "^6.0|^7.0|^9.0"
     },
     "autoload": {
         "psr-4": {