Auto merge of #5381 - lzutao:itertools, r=matthiaskrgr
Auto merge of #5381 - lzutao:itertools, r=matthiaskrgr

Bump itertools

changelog: none

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