Change scipy.stats.binom to use integer n

[seantur]

Hey @markmipt, thanks for your work on this package!

I noticed that the recently released scipy 1.9 was breaking things, and I tracked down the issue. Starting in scipy 1.9, binom will return NaN when n is not an integer.

The n value passed to the binom.pmf function is a float, so I just added in a round to make it an integer.

[markmipt]

Thanks!