change the hijri date

No try to it. That is the only option that you have. Subscribed calendars belong to the respective creator, and as a subscriber, you cannot edit that file. Your only option is to find a calendar that meets your requirements, or just create the holiday on your own.

If you are subscribing to the Holiday calendar, there is no way for you to change that date. You have no way to edit subscribed calendars, since you are not the owner. If you wish to create your own holiday listing, you can do that on your own calendar, or you can try to find a calendar subscription that meets your needs.