Drop or replace get_if_addrs due to future incompatibilities with rust due to winapi dep.

[CryoRenegade]

I will be the first to say that I dont know that much about programming in rust or how it works internally, but as an avid user of cli utils that are written in rust, with miniserve being a significant part of my operations (Seriously, u guys rock).
Earlier this month, i compiled miniserve on a windows server and got the warning that winapi would cause this project to stop compiling due to a old version on winapi. After a quick cargo tree, i found that get_if_addrs was the culprit and that it has been archived on github and is no longer being worked on.
With this, eventually miniserve will not work on windows (or at least x86_64-windows-msvc).
Heres a paste bin of the future-incompatibilities report (https://pastebin.com/4Bhuhjdt)

[mpipalia]

Looks like this functionality was moved into the if-addrs crate: https://crates.io/crates/if-addrs

[svenstaro]

I switched to if-addrs and all is well!