RequestBody not supported by operation macro

[Geekfish]

The operation macro currently supports passing arguments for url params, request body and response schemas in a "simplified" way (as tuples/keyword lists).

It also supports passing operation structs like %Parameter{} and %Response{}.

However, it doesn't support passing %RequestBody{}, for example this:

operation :update
  summary: "Update user",
  request_body: %RequestBody{
    #...
  }
  # ...

results in %Operation{requestBody: nil}.

The expected behaviour would be to return %Operation{requestBody: %RequestBody{}}.

I have submitted a simple fix here: #456