Tests fail on Windows

The following line is panicking on Windows:

https://github.com/BD103/migrate_rustdoc_json/blob/196aa8c0208667a1800715fe8f78407dae7d72f8/tests/utils/json.rs#L123

The panic was first caught in CI, [in this run](https://github.com/BD103/migrate_rustdoc_json/actions/runs/19475115227/job/55732792649), but the specific error is:

```
thread 'v42' (6332) panicked at tests\utils\json.rs:123:46:
called `Result::unwrap()` on an `Err` value: StripPrefixError(())
```

I'm disabling Windows support in CI for now, since I personally don't use it and would rather prioritize working on other features rather than debugging it in the VM. If someone figures out what's going wrong, feel free to open a PR!

Start at tests/utils/json.rs line 123 and review the linked GitHub Actions Windows run for the StripPrefixError. Reproduce the failing test on Windows, identify why the prefix operation returns an error, and confirm that the test no longer panics with Windows support restored in CI.

Written by the indexing model from the issue text.