api: fix string for localization

chrono/api/views.py

@@ -437,7 +437,10 @@ def get_event_text(event, agenda, day=None):
             date_format(localtime(event.start_datetime), 'DATETIME_FORMAT'),
         )
     elif event.recurrence_days:
-        event_text = _('%s: %s') % (WEEKDAYS[day].capitalize(), event_text)
+        event_text = _('%(weekday)s: %(event)s') % {
+            'weekday': WEEKDAYS[day].capitalize(),
+            'event': event_text,
+        }
     return event_text