Support diacritics in slug

[hopefourie-nyt]

Description of Change

Previously, character with diacritics dissapear in slug. For example, "Öğretmenelere Öneriler" becomes "retmenelere-neriler". Now, with a change to the regex, slugify is able to use it's built in functionality of transforming diacritics to it's non diacritic counterparts ş -> s, ç -> c etc.

• Edited regex that goes into slugify function
• Added a test for diacritics in slug

Related Issue

#267

Motivation and Context

Badly written slugs are a big issue for non-english internet and the links are less accessible.

Checklist

• Ran npm run lint and updated code style accordingly
• npm run test passes
• PR has a description and all contributors/stakeholder are noted/cc'ed
• tests are updated and/or added to cover new code
• relevant documentation is changed and/or added

[afischer]

Awesome! It would be great if we could continue to support the diacritics in the URL as well, but this seems like a good first step