notif [nfc]: Cut a redundant "it.let"

When the argument here was nullable, "it?.let" served a useful
purpose; but now that it's not, this can be cut out for a small
simplification.

Author: gnprice

android/app/src/main/kotlin/com/zulip/flutter/ZulipPlugin.kt

@@ -221,13 +221,13 @@ private class AndroidNotificationHost(val context: Context)
                 val style = NotificationCompat.MessagingStyle(toAndroidPerson(messagingStyle.user))
                     .setConversationTitle(messagingStyle.conversationTitle)
                     .setGroupConversation(messagingStyle.isGroupConversation)
-                messagingStyle.messages.forEach { it.let {
+                messagingStyle.messages.forEach {
                     style.addMessage(NotificationCompat.MessagingStyle.Message(
                         it.text,
                         it.timestampMs,
                         toAndroidPerson(it.person),
                     ))
-                } }
+                }
                 setStyle(style)
             }
             number?.let { setNumber(it.toInt()) }