write surveymail_date in sendmails command

TODO

@@ -12,7 +12,3 @@ other known problems:
 
 - The DatePicker works only if you are logged in, which is mostly ok for /intern
   and there is no Date to insert at the moment in forms for externs.
-
-missing features:
-
-- every modell should store the date when the surveymail was actually send.

input/management/commands/sendmails.py

@@ -84,6 +84,7 @@ class Command(BaseCommand):
                          name=myname,
                          realname=item.realname)
             item.survey_mail_send = True
+            item.survey_mail_date = date.today()
             item.save()
         self.stdout.write(self.style.SUCCESS(f'surveymails for object type {type} sent'))