add delay to testDuplicateMessage

tests/AgentTests/FunctionalAPITests.hs

@@ -762,6 +762,7 @@ testDuplicateMessage t = do
       get bob2 =##> \case ("", c, Msg "hello 3") -> c == aliceId; _ -> False
   disconnectAgentClient alice2
   disconnectAgentClient bob2
+  threadDelay 1000000
 
 testSkippedMessages :: HasCallStack => ATransport -> IO ()
 testSkippedMessages t = do