Fix AttributeError in ObjectSerializer by checking for __dict__ attribute

Co-authored-by: alexta69 <7450369+alexta69@users.noreply.github.com>

app/main.py

@@ -115,7 +115,7 @@ config = Config()
 
 class ObjectSerializer(json.JSONEncoder):
     def default(self, obj):
-        if isinstance(obj, object):
+        if hasattr(obj, '__dict__'):
             return obj.__dict__
         else:
             return json.JSONEncoder.default(self, obj)