Remove util/update_lints.py
Remove util/update_lints.py

This has been deprecated for ~10 months, so I think it's fine to remove now.

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