[EXTERNAL] Remove conflicting traits from expected data structure from rust-roman_numbers

[heshamalmosawi]

Why?

The expected functions and Usage of the roman_numbers task of the traits quest has a conflicting implementation of traits, aka duplicate usage of the debug trait, which leads to compilation error. This PR removes this conflict/duplication of traits.

Solution Overview

The solution only removes the duplicate trait from the readme, to remove the duplication and avoid the compilation error.

[pedrodesu]

Looks good to me! Thank you very much for spotting this mistake and submitting the PR. I should also warn you the team is working on refining and updating the Rust content comprehensively at the moment, so this type of mistake should be fixed promptly, as with other improvements that will be curated.