core: leak when using object member in a `RunnableSequence`

### Checked other resources - [x] I added a very descriptive title to this issue. - [x] I searched the LangChain documentation with the integrated search. - [x] I used the GitHub search to find a similar question and didn't find it. - [x] I am sure that this is a bug in LangChain rather than my code. - [x] The bug is not resolved by updating to the latest stable version of LangChain (or the specific integration package). ### Example Code ```python import gc from langchain_core.runnables import ( RunnableLambda, RunnablePassthrough, ) def log_memory_usage(): gc.collect() objs = gc.get_objects() print(f"Total objects: {len(objs)}") class ThingWithRunnable: def __init__(self, func): self.func = func self.runnable_lambda = RunnableLambda(func) self.expensive = {i: [i] for i in range(1000000)} def call(self, inputs): return self.runnable_lambda.invoke(inputs) def __del__(self): print(">>>> Cleaning up") def func(inp): return {"result": "ok"} def works(): thing = ThingWithRunnable(func) thing.call({}) def works2(): thing = ThingWithRunnable(func) (RunnableLambda(thing.func) | RunnablePassthrough()).invoke({}) def broken(): thing = ThingWithRunnable(func) (thing.call | RunnablePassthrough()).invoke({}) def broken2(): thing = ThingWithRunnable(func) (RunnableLambda(thing.call) | RunnablePassthrough()).invoke({}) if __name__ == "__main__": gc.freeze() print("Works:") for _ in range(2): works() log_memory_usage() print("Works 2:") for _ in range(2): works2() log_memory_usage() print("Broken:") for _ in range(2): broken() log_memory_usage() print("Broken 2:") for _ in range(2): broken2() log_memory_usage() ``` ### Error Message and Stack Trace (if applicable) _No response_ ### Description (I created this first as a discussion but after giving it some more thought, I'm pret…