Désactiver option "Je déclare être une structure" impossible

[Gredin67]

Describe the bug
If the member is declared as a structure, it cannot set back to an individual user.

To Reproduce
Steps to reproduce the behavior:

1. Go to https://manager.fablab-alsacenord.fr/#!/admin/members/
2. Désactiver "Je déclare être une structure"
3. Enregistrer
4. Retourner sur la fiche du membre
5. L'option est toujours cochée.

Expected behavior
Be able to change back to an individual user.

Server (please complete the following information):

• OS: YunoHost 12
• Kernel: [report here the result of uname -a]
• Fab-manager version 6.3.42

Browser (please complete the following information):

• Name: Firefox
• Version: 6.3.42