Refactor hook_lists initialization and add type hints

- Refactored the initialization of `hook_lists` to use a colon instead of an equal sign.
- Added type hints for the parameters and return types of `process_last_received_message` method.

autogen/agentchat/conversable_agent.py

@@ -242,7 +242,7 @@ def __init__(
 
         # Registered hooks are kept in lists, indexed by hookable method, to be called in their order of registration.
         # New hookable methods should be added to this list as required to support new agent capabilities.
-        self.hook_lists : Dict[str, List[Callable[[List[Dict]], List[Dict]]]] = {
+        self.hook_lists: Dict[str, List[Callable[[List[Dict]], List[Dict]]]] = {
             "process_last_received_message": [],
             "process_all_messages_before_reply": [],
             "process_message_before_send": [],
@@ -2724,7 +2724,7 @@ def process_all_messages_before_reply(self, messages: List[Dict]) -> List[Dict]:
             processed_messages = hook(processed_messages)
         return processed_messages
 
-    def process_last_received_message(self, messages:List[Dict]) -> List[Dict]:
+    def process_last_received_message(self, messages: List[Dict]) -> List[Dict]:
         """
         Calls any registered capability hooks to use and potentially modify the text of the last message,
         as long as the last message is not a function call or exit command.