Use the correct $dist-proposed-updates repository

Up to now, --proposed-updates always enabled kali-proposed-updates
when in fact it should have enabled the proposed-updates repository
of the target distribution.

auto/config

@@ -98,9 +98,9 @@ cp -rT kali-config/common config
 
 if [ -n "$enable_pu" ]; then
 	mkdir -p config/archives
-	echo "deb $kali_mirror kali-proposed-updates main contrib non-free" \
+	echo "deb $kali_mirror $dist-proposed-updates main contrib non-free" \
 		> config/archives/kali-proposed-updates.list.chroot
-	echo "deb $public_kali_mirror kali-proposed-updates main contrib non-free" \
+	echo "deb $public_kali_mirror $dist-proposed-updates main contrib non-free" \
 		> config/archives/kali-proposed-updates.list.binary
 fi