Capture extra args as Vec<String>

[ivarflakstad]

There is some merit to using &'static str, but it doesn't actually prevent bad usage as you could do something like Box::leak(String::new("my-string").into_boxed_str()).
Incidentally if you need to add an extra arg that is not static then the Box::leak approach is also the solution to get around this restriction. So imo good ol' String is a better choice.