Add Laravel 8 support

Author: unicodeveloper

composer.json

@@ -13,7 +13,7 @@
     "homepage": "https://github.com/cloudinary-labs/cloudinary-laravel",
     "keywords": ["Laravel", "cloudinary-laravel", "File Uploads", "Media Management", "Cloudinary", "File Transformations"],
     "require": {
-        "php": "^7.0",
+        "php": "^7.2",
         "illuminate/support": "~6|~7|~8",
         "cloudinary/cloudinary_php": "2.0.0-beta6",
         "ext-json": "*"