Hybrid search fail due to Text_key is stored in a nested field

[abdelsalamhamdi]

When performing the hybrid search the following code in libs/mongodb/langchain_mongodb/retrievers/hybrid_search.py cause a key value error if the text_key is a nested filed example title.text

# Formatting
        docs = []
        for res in cursor:
            text = res.pop(self.vectorstore._text_key)
            # score = res.pop("score")  # The score remains buried!
            make_serializable(res)
            docs.append(Document(page_content=text, metadata=res))
        return docs

[blink1073]

Hi @abdelsalamhamdi, thanks for raising the issue. We're tracking in https://jira.mongodb.org/browse/INTPYTHON-452.

[blink1073]

Fixed in #54