Fix a test that fails if backtraces are enabled due to different backtraces.

--- rust-hickory-resolver-0.24.4.orig/src/async_resolver.rs
+++ rust-hickory-resolver-0.24.4/src/async_resolver.rs
@@ -607,15 +607,19 @@ pub mod testing {
 
         use proto::error::{ProtoError, ProtoErrorKind};
 
-        let error_str = format!("{error}");
+        let mut error_str = format!("{error}");
         let name = Name::from_str("hickory-dns.org.").unwrap();
-        let expected_str = format!(
+        let mut expected_str = format!(
             "{}",
             ResolveError::from(ProtoError::from(ProtoErrorKind::RrsigsNotPresent {
                 name,
                 record_type: RecordType::A
             }))
         );
+        //hack to make tests pass if backtraces are enabled (as they are on debci)
+        error_str.truncate(100);
+        expected_str.truncate(100);
+
         assert_eq!(error_str, expected_str);
         if let ResolveErrorKind::Proto(_) = *error.kind() {
         } else {