Add United States Holidays

[arcdigital]

I've added all US Bank holidays.

[mikedex]

@arcdigital I would maybe consider adding all of the "bank" holidays. Without all of the federal holidays where the banks are closed, we would be unable to use this (I work in the finance industry). Thanks for submitting!

[arcdigital]

I've updated with all the bank holidays. The US is tricky but I think that makes the most sense.

[arcdigital]

Sure I can do that, yes it is a newer holiday. I'll add that logic in.

[arcdigital]

Just rebased it. I'll add the logic for Juneteenth.

[arcdigital]

@Nielsvanpach should be good to go! rebased, added the logic for Juneteenth, and a second test.

[Nielsvanpach]

Thanks!