Upgrade rust/crates/async-trait to 0.1.38

Change-Id: I894c990c19b1ac3d74e4bf002cf581b9875e730e
diff --git a/tests/ui/self-span.stderr b/tests/ui/self-span.stderr
index f897c01..fb11528 100644
--- a/tests/ui/self-span.stderr
+++ b/tests/ui/self-span.stderr
@@ -5,7 +5,7 @@
    | --------------- `S` defined here
 ...
 18 |         let _: Self = Self;
-   |                       ^^^^ did you mean `S { /* fields */ }`?
+   |                       ^^^^ help: use struct literal syntax instead: `S {}`
 
 error[E0308]: mismatched types
   --> $DIR/self-span.rs:17:21