Redirects not going to localized page

### Describe the bug

https://beeware.org/zh_CN/briefcase/ redirects to english page

### Steps to reproduce

Goto https://beeware.org/zh_CN/briefcase/

### Expected behavior

Redirects to Chinese page

### Screenshots

Irrelevant

### Environment

Irrelevant

### Logs

Irrelevant

### Additional context

None