Add test data for date conversion

[roozbehp]

I just typed in the leap year data from the Iranian calendar authority and put it at: https://github.com/roozbehp/persiancalendar/blob/main/kabise.txt

It would be great if automatic tests could be added based on that data to this project. (I expect all of them to pass.)

[slashmili]

Great idea!

only that the test will be for jalali-core as the algorithm resides there

[roozbehp]

You also have part of that algorithm here, in your isleap() method. I recommend either having it here or in both projects.

[slashmili]

fair point!