Add support for Laravel 7 (#6)

Author: jkudish

composer.json

@@ -12,7 +12,7 @@
     ],
     "require": {
         "php": "^7.2",
-        "illuminate/support": "^6.0",
+        "illuminate/support": "^6.0 || ^7.0",
         "symfony/polyfill-mbstring": "^1.0",
         "spatie/laravel-html": "^2.23"
     },