[feat] Upgrade to latest SuperAgent major version (10).

[mreishus]

Describe the feature

SuperTest is behind one major version. It depends on SuperAgent 9.x:

https://github.com/ladjs/supertest/blob/master/package.json#L9

However, SuperAgent released 10.x in August 2024: https://github.com/ladjs/superagent/releases/tag/v10.0.0

When I install the latest SuperAgent and SuperTest, my package.lock file has both 10.x and 9.x versions of SuperAgent installed.

Checklist

• [x] I have searched through GitHub issues for similar issues.
• [x] I have completely read through the README and documentation.