feat: make lastPacketDate accessible readonly

src/Client.js

@@ -123,10 +123,6 @@ export class Client extends EventEmitter {
         })
     }
 
-    get address() {
-        return this.#address
-    }
-
     async #publish(port, flags) {
         const response = await this.#protoRequest(PublishRequest.create({
             port,
@@ -183,4 +179,12 @@ export class Client extends EventEmitter {
             unpublish: flags => this.#unpublish(port)
         }
     }
+
+    get address() {
+        return this.#address
+    }
+
+    get lastPacketDate() {
+        return this.#lastPacketDate
+    }
 }