deps: Bump smol to 2.0 (#22956)

The collateral of this is that code size is increased by ~300kB, but I
think we can stomach it.

Release Notes:

- N/A

crates/terminal/src/terminal.rs

@@ -1731,9 +1731,9 @@ impl Terminal {
     pub fn wait_for_completed_task(&self, cx: &AppContext) -> Task<()> {
         if let Some(task) = self.task() {
             if task.status == TaskStatus::Running {
-                let mut completion_receiver = task.completion_rx.clone();
+                let completion_receiver = task.completion_rx.clone();
                 return cx.spawn(|_| async move {
-                    completion_receiver.next().await;
+                    let _ = completion_receiver.recv().await;
                 });
             }
         }