Add support for 'gpt-5.4' model (#947)

Author: aivis

src/Providers/OpenAI/Support/StructuredModeResolver.php

@@ -42,6 +42,7 @@ protected static function supportsStructuredMode(string $model): bool
             'gpt-5-nano',
             'gpt-5.1',
             'gpt-5.2',
+            'gpt-5.4',
         ]);
     }