Ipv4 type host is getting parsed as Domain type with uncommon scheme

[tkanakamalla]

Describe the bug
In case of an uncommon scheme, like udp, a Host::Ipv4 type is actually getting parsed as Host::Domain.

This is not a problem in case of an Ipv6 though.

here is an example:

fn main() {
    
    let y = url::Url::parse("udp://127.0.0.1").unwrap();
    println!("{y}");
    println!("{:?}", y.host());
    
    let y = url::Url::parse("http://127.0.0.1").unwrap();
    println!("{y}");
    println!("{:?}", y.host());
    
    let y = url::Url::parse("udp://[::1]").unwrap();
    println!("{y}");
    println!("{:?}", y.host());
}