make main blocking

src/main/kotlin/Main.kt

@@ -1,12 +1,14 @@
 import kotlinx.coroutines.GlobalScope
 import kotlinx.coroutines.delay
 import kotlinx.coroutines.launch
+import kotlinx.coroutines.runBlocking
 
-fun main(){
+fun main() = runBlocking{
     GlobalScope.launch {
         val mqtt = MqttSubscriber()
         mqtt.connect()
         delay(10000L)
         mqtt.disconnect()
     }
+    delay(20000L)
 }