Remove `#[feature(deprecated)]`
Remove `#[feature(deprecated)]`

Fixes `warning: this feature is stable. attribute no longer needed`.

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