Add thinking literal

Author: lcfyi

litellm/llms/anthropic/experimental_pass_through/adapters/streaming_iterator.py

@@ -31,7 +31,7 @@ class AnthropicStreamWrapper(AdapterCompletionStreamWrapper):
     sent_first_chunk: bool = False
     sent_content_block_start: bool = False
     sent_content_block_finish: bool = False
-    current_content_block_type: Literal["text", "tool_use"] = "text"
+    current_content_block_type: Literal["text", "tool_use", "thinking"] = "text"
     sent_last_message: bool = False
     holding_chunk: Optional[Any] = None
     holding_stop_reason_chunk: Optional[Any] = None