Update postgresql.sh

default Debian 12
fixes https://github.com/tteck/Proxmox/issues/1542

ct/postgresql.sh

@@ -23,7 +23,7 @@ var_disk="4"
 var_cpu="1"
 var_ram="1024"
 var_os="debian"
-var_version="11"
+var_version="12"
 variables
 color
 catch_errors