Serbian Cyrillic letters aren't transcripted to ASCII in URL slugs

[dimadin]

This is my first ticket, so sorry if I don't make it correctly.

We have some issue with URL slugs when using Serbian Cyrillic script in title. Letters are not converted to ASCII letters, as they are for example in Serbo-Croatian Latin script, so Cyrillic stay in URLs.

We have practice that in URLs Cyrillic is transliterated in Latin and then those non-ASCII Latin letters (š, ž, č, ć, đ) are also converted to Latin (s, z, c, c, dj, respectively).

Is there way that this be implemented, since users either write slugs manually or they even don't use post's titles in permalinks?

[Denis-de-Bernardy]

Merging into #9591.