tests: fixes facade test

Author: nunomaduro

tests/Facades/OpenAI.php

@@ -16,6 +16,8 @@
 
     (new ServiceProvider($app))->register();
 
+    OpenAI::setFacadeApplication($app);
+
     $completions = OpenAI::completions();
 
     expect($completions)->toBeInstanceOf(Completions::class);