Cannot get coverage report if c8 is running in a sub-directory & src is one level up.

* **9.1.0**:
* **MacOS**:

Hello! When I have c8 running from a sub-directory, I can't seem to get it to report coverage for src code that is one level up from where c8 is running.

- I have created this repo that reproduces the issue. https://github.com/timganter/c8-sub-directory
- Am I just configuring c8 incorrectly 🤞 ? [Here's my config](https://github.com/timganter/c8-sub-directory/blob/main/sub-directory/.c8rc.json).
- Or is this a bug?
- Here is a video showing the issue that can be reproduced [using this repo](https://github.com/timganter/c8-sub-directory).

https://github.com/bcoe/c8/assets/1911000/e871d7cd-9e92-492e-b178-a81ffe2d4b18