fix: add missing Dict/Optional imports in ChatGPT streaming_utils

Fixes NameError at runtime when ChatGPTToolCallNormalizer is
instantiated. The imports were missed when type hints were changed
from Python 3.10+ syntax (dict[], str | None) to typing module
syntax (Dict[], Optional[str]).

litellm/llms/chatgpt/chat/streaming_utils.py

@@ -4,7 +4,7 @@ Streaming utilities for ChatGPT provider.
 Normalizes non-spec-compliant tool_call chunks from the ChatGPT backend API.
 """
 
-from typing import Any
+from typing import Any, Dict, Optional
 
 
 class ChatGPTToolCallNormalizer:

tests/test_litellm/litellm_core_utils/test_streaming_handler.py

@@ -1274,6 +1274,7 @@ def test_usage_chunk_after_finish_reason_updates_hidden_params(logging_obj):
     assert hidden_usage.completion_tokens == 135, (
         f"Expected completion_tokens=135 from provider, got {hidden_usage.completion_tokens}"
     )
+
 @pytest.mark.asyncio
 async def test_custom_stream_wrapper_aclose():
     """Test that aclose() delegates to the underlying completion_stream's aclose()"""