Fix LXC updates

misc/build.func

@@ -501,6 +501,7 @@ start() {
   fi
 
   if ! command -v pveversion >/dev/null 2>&1; then
+    apt-get install -y whiptail
     if ! (whiptail --backtitle "Proxmox VE Helper Scripts" --title "${APP} LXC UPDATE" --yesno "Support/Update functions for ${APP} LXC.  Proceed?" 10 58); then
       clear
       echo -e "⚠  User exited script \n"