[fix] serve-index unable to update past 6.x

## Describe the bug

**Node.js version:** 22

**OS version:** Linux

**Description:**:

Currently, Supertest 7 is not able to run the [serve-index](https://github.com/expressjs/serve-index) tests properly, which prevents us from upgrading. I’m not sure why this is happening, but you can take a look at https://github.com/expressjs/serve-index/issues/117. I don’t have much more information at the moment.

## Checklist

- [x] I have searched through GitHub issues for similar issues.
- [x] I have completely read through the README and documentation.
- [x] I have tested my code with the latest version of Node.js and this package and confirmed it is still not working.