Update ipnetwork in pnet_datalink

[zer1t0]

Hi,

I'm working with interfaces of datalink and having problem with Ipv4NetworkIterator since it is a private type in ipnetwork "0.17.0". I have notice that the ipnetwork version was updated in the main project to "0.18.0", but not in pnet_datalink.

I think it could be possible to update ipnetwork to pnet_datalink to version "0.18.0" in order to maintain the same version that the one used in the main project.

Also I think it could be a good idea to update the version of the project to have the changes reflected in crates allowing to use the version "0.18.0" of ipnetwork.

Thank you for your work in this great project