Implement a new rule for FastApi routes

[TomerBin]

Hi there,

I recently came up with the idea to remove the redundant usage of the response_model keyword in FastAPI routes. FastAPI looks at the return type annotation of the decorated function by default, so using response_model while having a return type annotation with the same value is a code duplication that should be avoided.

As someone new to Rust and contributing to Ruff, I took this opportunity to learn and implemented this rule in #11579. If you find this rule aligns with Ruff’s goals, I would kindly ask for a code review.

Thank you!
Tomer Bin

[yannayh]

As someone using FastAPI that had no idea that this is a code duplication (which exists in my project unfortunately 😅) I would love for this rule to be implemented 👍🏼

[charliermarsh]

Added in #11579 -- thanks @TomerBin!