Success box upon the theme check has a broken link for GitHub repo

The last link in the success box has a broken link in it.

Goes to: [Theme Unit Tests](https://github.com/WPTRT/theme-unit-test)

<img width="1151" height="231" alt="Image" src="https://github.com/user-attachments/assets/4b81652b-9d57-451d-ade0-cf7f62ab6927" />