Option disabling `transliterate`

[tunnckoCore]

Heya, great one.

Can we add options.transliterate so we can disable transliteration? Defaulting to true if you will so.

https://github.com/sindresorhus/slugify/blob/b841d04d92533469714e586435ed4c1b3b451d8c/index.js#L46

to

string = options.transliterate ? transliterate(string, {customReplacements}) : string;