sdk-py: Add Sequence[dict] type to values param type for `update_…

…state()` (#2054)

### Summary
The LangGraph API supports a list of `dict` for the `values` field for
the `POST /threads/<thread_id>/state` endpoint.

Reference:
https://github.com/langchain-ai/langgraph-api/blob/main/api/openapi.json#L3005-L3021

libs/sdk-py/langgraph_sdk/client.py

@@ -1057,7 +1057,7 @@ async def get_state(
     async def update_state(
         self,
         thread_id: str,
-        values: dict,
+        values: Optional[Union[dict, Sequence[dict]]],
         *,
         as_node: Optional[str] = None,
         checkpoint: Optional[Checkpoint] = None,
@@ -3118,7 +3118,7 @@ def get_state(
     def update_state(
         self,
         thread_id: str,
-        values: dict,
+        values: Optional[Union[dict, Sequence[dict]]],
         *,
         as_node: Optional[str] = None,
         checkpoint: Optional[Checkpoint] = None,