[9.x] Add client_options to Pusher driver (#5743)

* Add client_options to Pusher driver

* Update broadcasting.php

Co-authored-by: Taylor Otwell <taylor@laravel.com>

config/broadcasting.php

@@ -39,6 +39,9 @@ return [
                 'cluster' => env('PUSHER_APP_CLUSTER'),
                 'useTLS' => true,
             ],
+            'client_options' => [
+                // Guzzle client options: https://docs.guzzlephp.org/en/stable/request-options.html
+            ],
         ],
 
         'ably' => [