chore: update to nx 18

[maiieul]

What is it?

• [ ] Feature / enhancement
• [ ] Bug
• [ ] Docs / tests
• [x] Other

Why is it needed?

• Using pnpm 8.15.8 because of https://github.com/qwikifiers/qwik-ui/issues/744
• Using nx 18.0.0 because of https://github.com/qwikifiers/qwik-ui/issues/746

Checklist:

• [ ] My code follows the developer guidelines of this project
• [ ] I have performed a self-review of my own code
• [ ] I have ran pnpm change and documented my changes
• [ ] I have add necessary docs (if needed)
• [ ] Added new tests to cover the fix / functionality

[changeset-bot[bot]]

⚠️ No Changeset found

Latest commit: 75548839e9cb46630c5ca1d52eeece860e392751

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[thejackshelton]

Other than what's mentioned above, preview & cloudflare build looks good.

Also playwright and the tests are in a similar state to before the upgrade 👍