Update cargo.
Update cargo.

This includes https://github.com/rust-lang/cargo/pull/4447 which fixes
a bug in Cargo that is needed to fix
https://github.com/rust-lang/rust/issues/44237.

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