[easy][py] remove unused classes in openai.py

couple of classes were defined but not used. Tested this by "find all references" on each class. No results showed up, so its safe to remove them

python/src/aiconfig/default_parsers/openai.py

@@ -366,24 +366,6 @@ def id(self) -> str:
  return self.model_id
 
 
-class GPT4Parser(DefaultOpenAIParser):
- def __init__(self):
- model_id = "gpt-4"
- super().__init__(model_id)
-
-
-class GPT3TurboParser(DefaultOpenAIParser):
- def __init__(self):
- model_id = "gpt-3.5-turbo"
- super().__init__(model_id)
-
-
-class ChatGPTParser(DefaultOpenAIParser):
- def __init__(self):
- model_id = "ChatGPT"
- super().__init__(model_id)
-
-
 def reduce(acc, delta):
  acc = copy.deepcopy(acc)