fix: support v18.x

[mmarchini]

• Remove closed() monkey-patch, rely on connectionState instead (GH-1888)
• fix IPv6 url by supporting new server.address().family format
• add node 18 to GH Actions

Co-authored-by: mary marchini oss@mmarchini.me

Pre-Submission Checklist

• [ ] Opened an issue discussing these changes before opening the PR
• [ ] Ran the linter and tests via make prepush
• [ ] Included comprehensive and convincing tests for changes

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What does this PR do?

[acommodari]

Hey 👋 Just checking in to see what the status of this PR is. I would love to be able to upgrade to node 18 but even with restify v9 I'm still unable to because of the monkey-patch. Even a very broad ETA would be great so my team can plan the node upgrade accordingly.

Thank you in advance and thanks for all the great work getting version 9 released!

[mmarchini]

We're aiming for the week of Nov 28