Bind kwargs to this chat model, returning a typed _ChatModelBinding.
Overrides Runnable.bind so the result preserves chat-model-specific
stream_events / astream_events overloads. Without this override,
model.bind(...).stream_events(version="v3") would type as
Iterator[Any] and await model.bind(...).astream_events(version="v3")
as Any, forcing callers to cast.
