fix: use correct Black version formatting for streaming_handler.py

Reformat with Black 23.x to match CI's version requirement.
The previous formatting commit used a newer Black version.

Signed-off-by: majiayu000 <1835304752@qq.com>

Author: majiayu000

litellm/litellm_core_utils/streaming_handler.py

@@ -127,9 +127,9 @@ def __init__(
 
         self.system_fingerprint: Optional[str] = None
         self.received_finish_reason: Optional[str] = None
-        self.intermittent_finish_reason: Optional[str] = (
-            None  # finish reasons that show up mid-stream
-        )
+        self.intermittent_finish_reason: Optional[
+            str
+        ] = None  # finish reasons that show up mid-stream
         self.special_tokens = [
             "<|assistant|>",
             "<|system|>",
@@ -1516,9 +1516,9 @@ def chunk_creator(self, chunk: Any):  # type: ignore  # noqa: PLR0915
                                                 t.function.arguments = ""
                             _json_delta = delta.model_dump()
                             if "role" not in _json_delta or _json_delta["role"] is None:
-                                _json_delta["role"] = (
-                                    "assistant"  # mistral's api returns role as None
-                                )
+                                _json_delta[
+                                    "role"
+                                ] = "assistant"  # mistral's api returns role as None
                             if "tool_calls" in _json_delta and isinstance(
                                 _json_delta["tool_calls"], list
                             ):