bug: `Binomial::entropy` returns `Some(0.0)` at `n = u64::MAX`, and panics on a debug build

[FBruzzesi]

Binomial::entropy() at n = u64::MAX returns Some(0.0). On a debug build the same call panics with attempt to add with overflow instead.

Every other n I tried returns a finite value, and the other moments at the same parameters are fine: mean and variance both return the expected finite numbers at n = u64::MAX. So this looks specific to entropy.

Environment: statrs main at 10cf6d610c1b8febc0b0606a443eb5e9d6ac8b7d, rustc 1.97.1, aarch64-apple-darwin

Reproducer

use statrs::distribution::Binomial;
use statrs::statistics::Distribution;

fn main() {
    let dist = Binomial::new(0.5, u64::MAX).unwrap();
    println!("{:?}", dist.entropy());
}

$ cargo run --release
Some(0.0)

$ cargo run
thread 'main' panicked at src/distribution/binomial/mod.rs:222:17:
attempt to add with overflow