hide username_is_unique and email_is_unique fields (fixes #8016)

They are not needed in the Pr@tic context.

src/authentic2_pratic/forms.py

@@ -49,7 +49,7 @@ class CertificateMixin(forms.ModelForm):
 class CollectivityForm(CertificateMixin, BaseForm):
     class Meta:
         model = models.Collectivity
-        exclude = ('uuid', 'default')
+        exclude = ('username_is_unique', 'email_is_unique', 'uuid', 'default')
 
 class ServiceInstanceForm(BaseForm):
     def clean(self):