I have looked at the following issue. In fact faraday allows us to access options using `[]=` https://github.com/lostisland/faraday/blob/master/lib/faraday/options.rb#L195 but the available options are set using a `Struct` which do not allow to set custom attributes at runtime.

Either we should ask faraday owners to implement a new feature allowing us to set custom attributes at runtime or handle ourselves per-request options.