add assistant beta header

Author: frithjof

src/Resources/config/services.php

@@ -17,6 +17,7 @@
         ->set(Factory::class)
         ->factory([OpenAI::class, 'factory'])
         ->call('withHttpClient', [service('openai.http_client')])
+        ->call('withHttpHeader', ['OpenAI-Beta' , 'assistants=v1'])
 
         ->set(Client::class)
         ->factory([service(Factory::class), 'make'])