os.ReadFile/WriteFile replace ioutil

新版本的变更 / Go 1.16

import (
"io/ioutil"
"os"
)

// *** before: ***
data, err := ioutil.ReadFile("config.json")
err = ioutil.WriteFile("out.json", data, 0644)

// *** in version 1.16: ***
data, err := os.ReadFile("config.json")
err = os.WriteFile("out.json", data, 0644)