Fix color of strike-through line for cancelled lessons

aleksis/apps/chronos/frontend/components/calendar_feeds/event_bar/LessonEventBar.vue

@@ -14,6 +14,7 @@
           'orange-border':
             selectedEvent.meta.amended && !selectedEvent.meta.cancelled,
           'red-border': selectedEvent.meta.cancelled,
+          'text-decoration-line-through': selectedEvent.meta.cancelled,
         }"
         :style="{
           color: currentSubject ? currentSubject.colour_fg || 'white' : 'white',