add missing newline

main/main.go

@@ -40,4 +40,4 @@ func main() {
 	fmt.Printf("The auction winner paid ¤%f, %s.\n", price, valueStr)
 	fmt.Printf("The item was worth ¤%f to them.\n", bidder.Value)
 	fmt.Printf("They would have paid up to ¤%f for it.\n", bidder.BidCeiling())
-}
+}