fix empty attribute options on unsupported language
steps to reproduce
- with a fresh user (who has not yet set user.language) set the browser language to french (or any other language except for en and de)
- go to the attributes tab in subject management
- examine the options for handedness
expected behavior
- "Inconnu", "Right", "Left", "Ambidextrous"
actual behavior
- "Inconnu"
solution
See https://django-parler.readthedocs.io/en/stable/quickstart.html#filtering-translations