update OnlinePythonTutor to fix comparison issue

When I made my string comparison fix to pytutor.js, I didn't do it quite right and actually made the problem worse (*no* correct answer would be recognized as such.) It looks like it's already been fixed, so I updated the submodule.

I've really got to start testing this stuff better!

Edit: looks like it was you that made the fix anyway. If you've already updated the submodule go ahead and disregard this pull request.