rust: Use 2021 eition
No functional changes.
The 2015 edition has some inconsistent syntax around use within a scope which has been bugging me, but don't remember.
Since we now use mozilla-rustc, I decided to jump 2 versions forward at once.
No functional changes.
The 2015 edition has some inconsistent syntax around use within a scope which has been bugging me, but don't remember.
Since we now use mozilla-rustc, I decided to jump 2 versions forward at once.