Simplify should_panic messages on tests

[ggonzalez94]

🧐 Motivation
Most of the tests that should panic and use felt252 for the error message are using a tuple of felt252 instead of a single value, even when there's only one value(e.g. #[should_panic(expected: ('Caller is missing role',))]).
The syntax is cluttered and could be simplified(e.g. #[should_panic(expected:'Caller is missing role')])