[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 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

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