get-size-derive is unmaintained

get-size-derive's maintainer seems to be unreachable, with no commits and releases pushed for 1 year and no activity on the GitHub repo.

get-size-derive also depends on `attribute-derive ^0.6` a version of the crate which uses the yanked crate `proc-macro-error`.

## Possible Alternative(s)

- [get-size-derive2](https://crates.io/crates/get-size-derive2)