Add loading animation

aleksis/apps/chronos/frontend/components/SelectTimetable.vue

@@ -106,6 +106,11 @@ export default {
           </v-list-item-group>
         </v-list>
       </template>
+      <template #loading>
+        <v-skeleton-loader
+          type="list-item-avatar,list-item-avatar,list-item-avatar"
+        />
+      </template>
     </v-data-iterator>
   </div>
 </template>