use utf8mb4 as default character set

config/database.php

@@ -59,8 +59,8 @@ return [
             'database' => env('DB_DATABASE', 'forge'),
             'username' => env('DB_USERNAME', 'forge'),
             'password' => env('DB_PASSWORD', ''),
-            'charset' => 'utf8',
-            'collation' => 'utf8_unicode_ci',
+            'charset' => 'utf8mb4',
+            'collation' => 'utf8mb4_unicode_ci',
             'prefix' => '',
             'strict' => true,
             'engine' => null,