deps: bump itertools 0.8 -> 0.9
deps: bump itertools 0.8 -> 0.9

changelog: none

graydon/rust,graydon/rust,aidancully/rust,aidancully/rust,aidancully/rust,graydon/rust,graydon/rust,aidancully/rust,aidancully/rust,graydon/rust,aidancully/rust,graydon/rust