DeepSeek Integration for LangChain

langchain-deepseek is an official LangChain partner package that integrates DeepSeek's large language models (LLMs) and embeddings into the LangChain ecosystem. It allows developers to easily use DeepSeek models for chat completions and text embeddings within their LangChain applications. The current version is 1.0.1, and it follows the rapid development and release cadence typical of LangChain's partner libraries, often aligning with `langchain-core` updates.