♻️ Use a better method to not create a pointer

src/views/TimetableView.vue

@@ -10,7 +10,7 @@ const timetable = computed(() => {
   const currentDay = parsedTimetable.value[timetableDay.value];
   if (!currentDay) return [];
   const newDay = currentDay.map((e, index) => {
-    const newElement = JSON.parse(JSON.stringify(e));
+    const newElement = { ...e };
     newElement.substitution = substitutions.value.find((entry) => {
       const entryDay = new Date(entry.date).getDay() - 1;
       return entry.lesson == index + 1 && entryDay == timetableDay.value;