Use once_cell instead of lazy_static

This seems to be generally considered the preferred, idiomatic solution
now. This is in the standard library behind a feature flag (apparently
now called `std::sync::LazyLock`).

examples/websocket/src/main.rs

@@ -8,6 +8,7 @@ use iced::widget::{
 use iced::{
     Application, Color, Command, Element, Length, Settings, Subscription, Theme,
 };
+use once_cell::sync::Lazy;
 
 pub fn main() -> iced::Result {
     WebSocket::run(Settings::default())
@@ -165,6 +166,4 @@ impl Default for State {
     }
 }
 
-lazy_static::lazy_static! {
-    static ref MESSAGE_LOG: scrollable::Id = scrollable::Id::unique();
-}
+static MESSAGE_LOG: Lazy<scrollable::Id> = Lazy::new(scrollable::Id::unique);