selected date is not flagged when using a different calendar of dayjs

[Javid-Izadfar]

I've imported dayjs right from @alibaba-aero/vue-calendar and used it with jalali calendar.

the issue I'm facing is, when I fill selections array with a jalali date (like '1400/03/29'), I get selected: false prop on DayView component.

I think the issue is:
When finding the month index in calendar.vue, a simple YYYY/MM/DD date string would break everything. at line 156 there is a different instance of dayjs with a different calendar (gregorian calendar).

Transforming my jalali date string to equivalent gregorian one was useless because then at month.vue I wouldn't be able to check if it's selected or not.

what I suggest is to format each item at line 156 to make sure keys match.

[Javid-Izadfar]

I'd open a MR if you guys also think this is the issue