Fix test dependency

I was going to let this module die a slow death per

    https://github.com/lestrrat/p5-HTML-HeadParser-Liberal/pull/2#issuecomment-42647163

but then on New Year's Eve I get this:

    http://twitter.com/louis_rouxel/status/550242879281856512
    http://twitter.com/louis_rouxel/status/550255221780512769

So I guess there is *some* value in keeping this module alive...

fixes #1 and refs #2