Depends on outdated linked-hash-map

[RalfJung]

The linked-hash-map crate release 0.5.3 contained a critical bugfix; older releases might stop working when the compiler is able to better detect misuses of uninitialized memory (https://github.com/rust-lang/rust/pull/71274). Would be great if you could update the dependency of your crate to use the latest version. :)