core[patch]: bump langsmith (#22476)

Noticing errors logged in some situations when tracing with Langsmith:
```python
from langchain_core.pydantic_v1 import BaseModel
from langchain_anthropic import ChatAnthropic


class AnswerWithJustification(BaseModel):
    """An answer to the user question along with justification for the answer."""
    answer: str
    justification: str


llm = ChatAnthropic(model="claude-3-haiku-20240307")
structured_llm = llm.with_structured_output(AnswerWithJustification)

list(structured_llm.stream("What weighs more a pound of bricks or a pound of feathers"))
```
```
Error in LangChainTracer.on_chain_end callback: AttributeError("'NoneType' object has no attribute 'append'")
[AnswerWithJustification(answer='A pound of bricks and a pound of feathers weigh the same amount.', justification='This is because a pound is a unit of mass, not volume. By definition, a pound of any material, whether bricks or feathers, will weigh the same - one pound. The physical size or volume of the materials does not matter when measuring by mass. So a pound of bricks and a pound of feathers both weigh exactly one pound.')]
```

libs/core/pyproject.toml

@@ -11,7 +11,7 @@ repository = "https://github.com/langchain-ai/langchain"
 [tool.poetry.dependencies]
 python = ">=3.8.1,<4.0"
 pydantic = ">=1,<3"
-langsmith = "^0.1.65"
+langsmith = "^0.1.66"
 tenacity = "^8.1.0"
 jsonpatch = "^1.33"
 PyYAML = ">=5.3"