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/collab/src/tests/integration_tests.rs

@@ -4936,7 +4936,7 @@ async fn test_project_search(
 
     // Perform a search as the guest.
     let mut results = HashMap::default();
-    let mut search_rx = project_b.update(cx_b, |project, cx| {
+    let search_rx = project_b.update(cx_b, |project, cx| {
         project.search(
             SearchQuery::text(
                 "world",
@@ -4951,7 +4951,7 @@ async fn test_project_search(
             cx,
         )
     });
-    while let Some(result) = search_rx.next().await {
+    while let Ok(result) = search_rx.recv().await {
         match result {
             SearchResult::Buffer { buffer, ranges } => {
                 results.entry(buffer).or_insert(ranges);