[Improvement]: remove dependency on proc_macro_error

[nicolasauler]

Describe the improvement

It seems that the proc_macro_error crate is flagged as unmaintained.

That is used on shuttle_codegen.

Is there any way in which we can upgrade from that crate?

Duplicate declaration

• [X] I have searched the issues and this improvement has not been requested before.

[JuliDi]

Seems like proc-macro-error-2 could be used as a drop-in replacement since it's a fork of the unmaintained original: https://crates.io/crates/proc-macro-error2

[c-git]

Add the error message from cargo deny so that others can find this issue more easily

ID: RUSTSEC-2024-0370
    = Advisory: https://rustsec.org/advisories/RUSTSEC-2024-0370
    = proc-macro-error's maintainer seems to be unreachable, with no commits for 2 years, no releases pushed for 4 years, and no activity on the GitLab repo or response to email.
      
      proc-macro-error also depends on `syn 1.x`, which may be bringing duplicate dependencies into dependant build trees.
      
      ## Possible Alternative(s)
      
      - [manyhow](https://crates.io/crates/manyhow)
      - [proc-macro-error2](https://crates.io/crates/proc-macro-error2)
      - [proc-macro2-diagnostics](https://github.com/SergioBenitez/proc-macro2-diagnostics)
    = Announcement: https://gitlab.com/CreepySkeleton/proc-macro-error/-/issues/20
    = Solution: No safe upgrade is available!

[Aditya-PS-05]

@jonaro00 , I would like to work on this issue. Can you assign me this issue?