Wrapper around blackd using poetry

Why?

For some reason I couldn't get blackd to run as a Render private service so instead I just added a FastAPI layer on top of it and it worked so now I don't want to touch this service.

How is this service used?

1. In development it is convenient to start blackd along with yarn dev in konfig-dash. Our CLI will simply use the locally running blackd instance.
2. In production blackd is wrapped in its own FastAPI service and accessible through the /formatPython endpoint at our REST API which then proxies the request to the FastAPI service. Our CLI uses this REST API in production mode.