tour: Korean language is broken

Context: https://go.dev/tour/welcome/2

Korean version is responding with an error ([ref](https://go-tour-ko.appspot.com/)):
<img width="522" alt="Image" src="https://github.com/user-attachments/assets/97aa3b66-a12e-4526-bd29-b9b0ed2c60ea" />

All other languages appear to be working.