style(client): reformat imports in test files

Collapse multi-line import statements into single lines to improve code legibility and maintain consistent formatting across test suites.

crates/irtt-client/tests/hmac.rs

@@ -3,8 +3,7 @@ mod support;
 use std::time::Duration;
 
 use irtt_client::{
-    Client, ClientConfig, ClientError, ClientEvent, OpenOutcome, SocketConfig,
-    WarningKind,
+    Client, ClientConfig, ClientError, ClientEvent, OpenOutcome, SocketConfig, WarningKind,
 };
 use irtt_proto::{echo_packet_len, ProtoError, TimestampFields};