upgrade

src/client/mod.rs

+use std::collections::HashSet;
+
 use serde::{Deserialize, Serialize};
 
 use crate::socket::protocol::Qos;
@@ -33,7 +35,7 @@ pub struct PushMessage {
 #[derive(Debug, Serialize, Deserialize)]
 #[serde(rename_all = "camelCase")]
 pub struct DeviceMessage {
-    pub devices: Vec<String>,
+    pub devices: HashSet<String>,
     pub business_type: i32,
     pub message_id: i64,
     pub key: Option<String>,