Fix push notification styling backwards compatibility (#8913)

app/notification.go

@@ -722,6 +722,7 @@ func (a *App) sendPushNotification(post *model.Post, user *model.User, channel *
 		msg.Badge = int(badge.Data.(int64))
 	}
 
+	msg.Version = model.PUSH_MESSAGE_V2
 	msg.Type = model.PUSH_TYPE_MESSAGE
 	msg.TeamId = channel.TeamId
 	msg.ChannelId = channel.Id

model/push_notification.go

@@ -17,6 +17,7 @@ const (
 
 	PUSH_TYPE_MESSAGE = "message"
 	PUSH_TYPE_CLEAR   = "clear"
+	PUSH_MESSAGE_V2   = "v2"
 
 	// The category is set to handle a set of interactive Actions
 	// with the push notifications
@@ -44,6 +45,7 @@ type PushNotification struct {
 	OverrideUsername string `json:"override_username"`
 	OverrideIconUrl  string `json:"override_icon_url"`
 	FromWebhook      string `json:"from_webhook"`
+	Version          string `json:"version"`
 }
 
 func (me *PushNotification) ToJson() string {