Remove code for updating copyright years in generate-deriving-span-tests
Remove code for updating copyright years in generate-deriving-span-tests

It's no longer necessary, as there is no license header anymore.

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