fix number input event

mc_frontend/src/app/exercise-list/exercise-list.page.html

@@ -93,7 +93,7 @@
                                     <br>{{'VOCABULARY_REFERENCE_RANGE_END' | translate}}</h6>
                                 <ng-template #hasFrequencyOrder>
                                     <input type="number" [(ngModel)]="vocService.frequencyUpperBound"
-                                           name="frequencyUpperBound" (change)="hasVocChanged = true"/>
+                                           name="frequencyUpperBound" (input)="hasVocChanged = true"/>
                                 </ng-template>
                             </label>
                         </ion-col>