fix: windows compatible unit tests

[tlaukkanen]

This pull request includes changes to improve cross-platform compatibility and refactor file handling in the test suite. The most significant changes include adding platform-specific newline characters, refactoring path handling (path.join(...) handles the folder separator characters), and updating readFile import statement so that vi.mock('fs/promises'... works on Windows too.

Tested the changes by running npm test with both Windows (GitBash terminal) and on Linux via WSL.

Windows:

Linux (via WSL):

[tlaukkanen]

Additionally I think this will also fix the isValidProject outcome on Windows as previously it was causing this while loop to run continuosly in getDependencyFile in case it didn't find any dependency files. So, this should help with issues like #65 and #43

[steve8708]

thanks @tlaukkanen !