Incorrect characters for number keys on Czech layout

[p0deje]

Thank you for creating this library, it's been essential for my clipboard manager - https://github.com/p0deje/Maccy. I can't even imagine handling all the complexity of converting keycodes to characters and back myself. 🙏🏻

I have been investigating one of the bugs reported by users p0deje/Maccy#482 (comment) and it seems like it could be a problem in the Sauce library itself.

On specific keyboard layouts, for example, Czech, the numbers row is mapped to accented characters and numbers are available by pressing ⇧.

I am trying to find a proper character to pass to NSMenuItem.keyEquivalent and I would normally do something like this:

let keyCode = Sauce.shared.keyCode(for: .one)
let char = Sauce.shared.character(for: Int(keyCode), cocoaModifiers: [])
// ▿ Optional<String>
//  - some : "1"

However, I would expect "+" to be returned in this case. I traced the problem to CoreServices.UCKeyTranslate but I'm not sure how to properly use it to find a necessary character.

I would happily submit PR to fix the problem but need some guidance.