trace: adds back call to classify_eos on trailers

- was dropped in the http-body 1.0 upgrade

tower-http/src/trace/body.rs

@@ -62,6 +62,13 @@ where
 
                 let frame = match frame.into_trailers() {
                     Ok(trailers) => {
+                        if let Some((classify_eos, mut on_failure)) =
+                            this.classify_eos.take().zip(this.on_failure.take())
+                        {
+                            if let Err(failure_class) = classify_eos.classify_eos(Some(&trailers)) {
+                                on_failure.on_failure(failure_class, latency, this.span);
+                            }
+                        }
                         if let Some((on_eos, stream_start)) = this.on_eos.take() {
                             on_eos.on_eos(Some(&trailers), stream_start.elapsed(), this.span);
                         }