getActualMaximum() is broken

[archmageirvine]

I believe the function getActualMaximum() should return a value appropriate to the current date, so that for example getActualMaximum(Calendar.DAY_OF_MONTH) should return the maximum day number in the current month for the current date. Currently this always returns 31 which is incorrect.

[hadilq]

Thank you for your contribution. It's a long time that I didn't use this library in my projects so I couldn't spend time to fix its problems. Let's see if I could manage to take a look this time 🤞