Concurrent script runs for build and dev on Windows

[alexanderkirtzel]

Describe the bug
It seems that the "dev": "npm run dev:build & npm run dev:test" commands are not executing as intended on a Windows machine.

To Reproduce
Steps to reproduce the behavior:
Run turbo run dev and see that only the build gets executed or at least shown.

Expected behavior
Both should run and get recalled due to the watch mode to test newly saved files and build a dev version for easier cross-package development.