support joi v18 as a peer dependency

[sulaysumaria]

• Widens the joi peer dependency range to ^17.0.0 || ^18.0.0 so projects using joi 18 aren't blocked by the resolver's peer dependency constraint.
• Bumps the joi devDependency to ^18.2.3 so the test suite actually runs and is verified against joi 18, not just joi 17.
• This is purely a dependency range fix. All existing joi resolver tests pass unmodified against joi 18.
• joi 17 support is kept in the peer range (rather than being replaced) to avoid a breaking change for existing consumers who haven't upgraded yet.

[sulaysumaria]

@bluebill1049 , Can you check this?

[github-actions]

🎉 This PR is included in version 5.9.0 🎉

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

Your semantic-release bot 📦🚀