fix: Use database route table instead of private route table for NAT gateway route (#476)

main.tf

@@ -255,7 +255,7 @@ resource "aws_route" "database_internet_gateway" {
 resource "aws_route" "database_nat_gateway" {
   count = var.create_vpc && var.create_database_subnet_route_table && length(var.database_subnets) > 0 && false == var.create_database_internet_gateway_route && var.create_database_nat_gateway_route && var.enable_nat_gateway ? local.nat_gateway_count : 0
 
-  route_table_id         = element(aws_route_table.private.*.id, count.index)
+  route_table_id         = element(aws_route_table.database.*.id, count.index)
   destination_cidr_block = "0.0.0.0/0"
   nat_gateway_id         = element(aws_nat_gateway.this.*.id, count.index)