Add support for Laravel 8.x (#7)

Authored-by: Yanis <[email protected]>

Author: ingalless

Diff for: README.md

@@ -29,4 +29,5 @@ Add the configuration to your mail.php config file:
 | Our Version | Supported Laravel Version |
 |-------------|---------------------------|
 | 1.x.x       | 5.5.x                     |
-| 2.x.x       | 7.x                       |
+| ^2.0        | 7.x                       |
+| ^2.0.2      | 8.x                       |

Diff for: composer.json

@@ -23,7 +23,7 @@
     "require": {
         "php": "^7.2.5|^8.0",
         "guzzlehttp/guzzle": "^6.3.1|^7.0.1",
-        "laravel/framework": "^7.0"
+        "laravel/framework": "^7.0|^8.0"
     },
     "extra": {
         "laravel": {