Duration::new panics in Readable impl

[caibear]

speedy = "0.8.7"

use speedy::Readable;
let _ = std::time::Duration::read_from_buffer(&[255; 12]);

Results in thread 'main' panicked at 'overflow in Duration::new. Could fix by checking nanos < 1_000_000_000 before calling Duration::new in speedy::Readable since speedy::Writable uses Duration::subsec_nanos which always meets that requirement.