RUSTSEC-2024-0370: proc-macro-error is unmaintained

> proc-macro-error is unmaintained

| Details | |
| ------------------- | ---------------------------------------------- |
| Status | unmaintained |
| Package | `proc-macro-error` |
| Version | `1.0.4` |
| URL | [https://gitlab.com/CreepySkeleton/proc-macro-error/-/issues/20](https://gitlab.com/CreepySkeleton/proc-macro-error/-/issues/20) |
| Date | 2024-09-01 |

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)

See [advisory page](https://rustsec.org/advisories/RUSTSEC-2024-0370.html) for additional details.

The issue names the proc-macro-error 1.0.4 package and lists manyhow, proc-macro-error2, and proc-macro2-diagnostics as alternatives, but no repository file, test, or entry point. Start by locating the package in the dependency manifests and checking which alternative is compatible. Done means the unmaintained dependency is removed without breaking the build or its tests.

Written by the indexing model from the issue text.