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

[github-actions[bot]]

Details
Package	proc-macro-error
Version	1.0.4
Warning	unmaintained
URL	https://gitlab.com/CreepySkeleton/proc-macro-error/-/issues/20
Patched Versions	n/a

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
• proc-macro-error2
• proc-macro2-diagnostics

[elenakrittik]

We depend on this through tabled, so we'll need to wait for https://github.com/zhiburt/tabled/pull/428.