update uswds to 3.0 version

[jaredbain]

Fixes #463

Checklist

• My code follows the existing style, code structure, and naming taxonomy
• I have performed a self-review of my own code and have no open issues
• I have commented my code, particularly in hard-to-understand areas
• My changes generate no new warnings or syntax errors
• I have verified Draft on actual mobile devices, especially Safari-based

[Dahianna]

We'll implement the external icon on the page manually and backlog this update. We'll look into possibly moving the website from Jekyll to another site generator like https://www.11ty.dev/