Avoid using `ptr::Unique` in `LinkedList` code Addresses a [comment](https://github.com/rust-lang/rust/pull/103093#discussion_r1268506747) by `@RalfJung` about avoiding use of `core::ptr::Unique` in the standard library.
Avoid using `ptr::Unique` in `LinkedList` code Addresses a [comment](https://github.com/rust-lang/rust/pull/103093#discussion_r1268506747) by `@RalfJung` about avoiding use of `core::ptr::Unique` in the standard library.