#92 ddclient 3.9.0 requires non-standard Data::Validate::IP

[Andreas M. Kirchwitz]

ddclient 3.9.0 introduces a requirement of Perl module "Data::Validate::IP" which is not part of a standard Perl installation. The only function used is "is_ipv6". Maybe simply checking for a colon would be sufficient in this specific context. This would avoid this non-standard requirement and keep ddclient easy to install.