fix: Make spawn process work on Windows

[joachimvh]

This would make my life easier.

The Windows installation of eye is done with a batch file, which requires this setting as noted in https://nodejs.org/api/child_process.html#spawning-bat-and-cmd-files-on-windows

I also changed the eye path in the test to eye from /usr/local/bin/eye so it is platform independent. Or does that break stuff for you?

[woutslabbinck]

Test script still works on my machine, so this change ensure ODRL evaluator can work with local eye on both windows and linux.