chore: ioutil.Discard, ioutil.ReadFil and ioutil.TempFile, is deprecated

[maxwelbm]

// Deprecated: As of Go 1.16, this value is simply [io.Discard].
var Discard io.Writer = io.Discard

// Deprecated: As of Go 1.17, this function simply calls [os.CreateTemp].
func TempFile(dir, pattern string) (f *os.File, err error) {

// Deprecated: As of Go 1.16, this function simply calls [os.ReadFile].
func ReadFile(filename string) ([]byte, error) {