Test example triggers false positive Socket alert

It is totally clear to me that this code ([/tests/ui/non-quotable.rs](https://github.com/dtolnay/quote/blob/master/tests/ui/not-quotable.rs))

```rust
fn main() {
let ip = Ipv4Addr::LOCALHOST;
let _ = quote! { #ip };
}
```

does not approach anywhere close to accessing the network, but [explain this for Socket](https://socket.dev/cargo/package/quote/files/1.0.45/quote-1.0.45/tests/ui/not-quotable.rs#T22-40)!

I suggest thinking of a less provocative example that would not trigger confusing alerts.