make client singleton

Author: BinaryKitten

src/Providers/TalkJSServiceProvider.php

@@ -17,7 +17,7 @@ public function register(): void
             'talkjs'
         );
 
-        $this->app->bind(
+        $this->app->singleton(
             TalkJSClient::class,
             static function ($app, $params) {
                 $appId = $params['appId'] ?? config('talkjs.app_id');