Supply datetimes as utc

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

@@ -157,8 +157,8 @@ export default {
       return {
         ...item,
         amends: this.selectedEvent.meta.id,
-        datetimeStart: this.selectedEvent.startDateTime.toUTC().toISO(),
-        datetimeEnd: this.selectedEvent.endDateTime.toUTC().toISO(),
+        datetimeStart: this.$toUTCISO(this.selectedEvent.startDateTime),
+        datetimeEnd: this.$toUTCISO(this.selectedEvent.endDateTime),
         // Normalize cancelled, v-checkbox returns null & does not
         // honor false-value.
         cancelled: item.cancelled ? true : false,