Upgrade to new dns lib version; that saw multiple improvements; some
patch releases are in the pipeline.

The big thing here is the removal of ErrTruncated, so we need to deal
with this slightly different in the forward plugin. It removed the
entire truncated.go logic and just checks the message for .Truncated (if
there is a message) and retries with tcp.
Signed-off-by: Miek Gieben <miek@miek.nl>