Steps to reproduce

1. Install Ibexa DXP
2. Go to place where slug is generate automatically via JS e.g  Attribute groups
3. Create a new attribute group and as name set "Söder"

Result

The Identifier was generate wrongly as Soder

Expected

Slug generation should be works correctly for any languages dialect. Generating a slug using PHP works correctly (for example create an article and use Söder as the name)