Upgrade to use Node.js 20 and bump npm dependencies

[eason9487]

Changes proposed in this Pull Request:

The end-of-life for Node.js v18 is April 30, 2025, which is still about 10 months away, but there should be no harm in aligning with the same version used in WooCommerce core early!

This PR:

• Upgrade to use Node.js v20
• Bump dependencies
  • Add @wordpress/url to dev dependencies as it's no longer a dependency under @wordpress/scripts

Checks:

• Does your code follow the WordPress coding standards?
• Have you written new tests for your changes, as applicable?
• Have you successfully run tests with your changes locally?
• Have you checked to ensure there aren't other open Pull Requests for the same update/change?

Detailed test instructions:

1. Set Node.js to v20
2. Run npm install to see if it can finish without errors
3. Check if the following scripts work well
   • npm start
   • npm run dev
   • npm run build
   • npm run lint:js
4. Inspect the E2E test result on GitHub Actions or run it locally to see if all tests can pass

Changelog entry

• Dev - Upgrade to Node.js 20.
• Dev - Upgrade npm dependencies.

[martynmjones]

Hey @eason9487, thanks for the update!

No issues installing packages and all our scripts are working as expected ✅