Deprecate `node18` and re-enable audit workflow

Summary

We added a workflow in #3449 to audit our dependencies on release. However, it is currently disabled. After attempting to resolve the issue with a pnpm audit --fix, we ran into problems with the new dependencies that do not support Node 18.

1. Deprecate support for Node18.
2. Override/fix appropriate dependencies with a pnpm audit --fix
3. Enable the workflow to audit our packages on release (ref).
4. Un-ignore the dependabot updates below and perform the upgrades

Ignored dependabot updates

• [email protected] requires [email protected], which only supports node 20 || >=22 (ignored here)
• [email protected] only supports node [20 || >=22].