Changed method of adding backport repo.

ntos/configs/minimal/preseed.cfg

@@ -48,8 +48,6 @@ d-i apt-setup/enable-source-repositories boolean false
 d-i apt-setup/disable-cdrom-entries boolean true
 
 d-i apt-setup/services-select multiselect security, updates
-d-i apt-setup/backports/repository string \
-    http://ftp.de.debian.org/debian bookworm-backports main
 d-i pkgsel/update-policy select full-upgrade
 d-i popularity-contest/participate boolean true
 
@@ -66,7 +64,9 @@ d-i grub-installer/force-efi-extra-removable boolean true
 d-i grub-installer/only_debian boolean true
 
 d-i preseed/late_command string \
-    in-target /bin/bash -c ' \
+    in-target /bin/bash -c '\
+    echo "deb http://ftp.de.debian.org/debian bookworm-backports main" > /etc/apt/sources.list/backport.list \
+    apt-get update
     apt-get install -y xfce4 xfce4-goodies xfce4-power-manager system-config-printer xfce4-panel-profiles xsane plymouth-themes dbus-x11 network-manager-gnome curl yad freerdp3-x11; \
     apt-get autoremove -y; \
     echo "NTOS-Setup" > /etc/hostname; \