x11-autologin: nopasswdlogin group for sddm too

See also this somewhat related conversation (in Russian):
https://forum.altlinux.org/index.php?topic=28619.345

features.in/x11-autologin/rootfs/image-scripts.d/40-x11-autologin

@@ -109,6 +109,8 @@ SDDM_RC=/etc/X11/sddm/sddm.conf
 SDDM_SESSION=
 if [ -f "$SDDM_RC" ]; then
 	backup "$SDDM_RC"
+	backup "/etc/group"
+	add_nopasswdlogin_group sddm ||:
 	sed -i "s,^User=$,&$USER," "$SDDM_RC"
 	if [ -f /usr/share/xsessions/lxqt.desktop ]; then
 		SDDM_SESSION=LXQt
@@ -119,6 +121,7 @@ if [ -f "$SDDM_RC" ]; then
 		sed -i "s,^Session=$,&$SDDM_SESSION," "$SDDM_RC"
 	fi
 	restore_later "$SDDM_RC"
+	restore_later "/etc/group"
 fi
 
 ## nodm autologin (the last since the most intrusive)