Add Regexp::IPv6 as test dependency

[XSven]

please consider the important RT issue unable to contact the remote mirror (without Regexp::IPv6?)

[briandfoy]

This is already #26, but I'll apply the change.

[briandfoy]

I've merged #26 in briandfoy/cpan-mini-inject in 93b6cef88c9269033d5592e360ed1841d438fff3. I can't close this issue, but look to the new repo for future work.