Langstream

Exposes the OpenAI instance being used through `OpenAIChatStream.client()`

This releases updates the implementation of OpenAI, LiteLLM and GPT4All for their latest versions, there are no breaking changes for LangStream since LangStream API wraps them entirely, except for the removal of the `stream` parameter on GPT4All, since it's no longer necessary to disable it to get replicate and others to work properly.

This release makes LLM implementation as optional dependencies, fixing 11, it might be a breaking change for you

Now, if you want to use langstream with say, OpenAI, you need to install the `openai` package separately, if you want to use with `gpt4all` or `litellm`, then you also need to install their packages separately, and so on

- Add support to [LiteLLM](https://github.com/BerriAI/litellm), bringing Azure, Anthropic, HuggingFace and many others to LangStream #10 ([docs](https://rogeriochaves.github.io/langstream/docs/llms/lite_llm))

**BREAKING:** LiteChain was renamed to LangStream! For more details check out 4

To migrate it should be easy enough, change the dependency and imports from `litechain` to `langstream`, and replace all matches of `chain` to `stream` and matches of `Chain` to `Stream` in your project

- Add `.pipe()` operator https://github.com/rogeriochaves/litechain/commit/26033e8a96e40fa98866df7604de7d2fe038d25a ([docs](https://rogeriochaves.github.io/litechain/docs/chain-basics/composing_chains#pipe))
- Add `.filter()` operator https://github.com/rogeriochaves/litechain/commit/33b18001c7757a8d734fa34a73a9a3031788cb29 ([docs](https://rogeriochaves.github.io/litechain/docs/chain-basics/composing_chains#filter))