🛠 Tooling: Don't transpile tests

[JoshuaKGoldberg]

Bug Report Checklist

• I have tried restarting my IDE and the issue persists.
• I have pulled the latest main branch of the repository.
• I have searched for related issues and found none that matched my issue.

Overview

@bradzacher mentioned in typescript-eslint/typescript-eslint#7056 (comment):

To me it seems weird to transpile tests - as the project grows this will slow down the build step a lot - which is why we are cautious to exclude them in this project. Imagine if our massive blob of fixtures was included in the transpiration then ignored by the publish - it'd be very slow!

Typechecking them - 100%, but transpiling them - no way!

Agreed. It's suboptimal that this repo transpiles tests unnecessarily. How to avoid it?

I'd rather not add multiple TSConfig files... maybe the repo should use tsup the way consumers such as https://github.com/JoshuaKGoldberg/ts-api-utils do? That would make it easier for consumers to add in dual CJS+ESM emit...

Additional Info

No response

[JoshuaKGoldberg]

Fixed by #640.