More test feature gating

Author: landonxjames

rust-runtime/aws-smithy-runtime/tests/dns_caching.rs

@@ -3,7 +3,11 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
-#![cfg(all(feature = "client", feature = "rt-tokio", not(target_family = "wasm")))]
+#![cfg(all(
+    feature = "client",
+    feature = "hickory-dns",
+    not(target_family = "wasm")
+))]
 
 use aws_smithy_runtime::client::dns::CachingDnsResolver;
 use aws_smithy_runtime_api::client::dns::ResolveDns;