Fix missing %s in callbacks.go

callbacks.go

@@ -75,7 +75,7 @@ func questionCallback(question alpm.QuestionAny) {
 			}
 
 			if num < 1 || num > size {
-				fmt.Printf(" invalid value: %d is not between %d and %d\n", red("error: "), num, 1, size)
+				fmt.Printf("%s invalid value: %d is not between %d and %d\n", red("error:"), num, 1, size)
 				continue
 			}