cleanup deprecated package io/ioutil (#4920)

Signed-off-by: zounengren <zouyee1989@gmail.com>

plugin/sign/file.go

@@ -3,7 +3,6 @@ package sign
 import (
 	"fmt"
 	"io"
-	"io/ioutil"
 	"os"
 	"path/filepath"
 
@@ -15,7 +14,7 @@ import (
 
 // write writes out the zone file to a temporary file which is then moved into the correct place.
 func (s *Signer) write(z *file.Zone) error {
-	f, err := ioutil.TempFile(s.directory, "signed-")
+	f, err := os.CreateTemp(s.directory, "signed-")
 	if err != nil {
 		return err
 	}

plugin/sign/keys.go

@@ -5,7 +5,7 @@ import (
 	"crypto/ecdsa"
 	"crypto/rsa"
 	"fmt"
-	"io/ioutil"
+	"io"
 	"os"
 	"path/filepath"
 	"strconv"
@@ -70,7 +70,7 @@ func readKeyPair(public, private string) (Pair, error) {
 	if err != nil {
 		return Pair{}, err
 	}
-	b, err := ioutil.ReadAll(rk)
+	b, err := io.ReadAll(rk)
 	if err != nil {
 		return Pair{}, err
 	}

plugin/sign/signer_test.go

@@ -1,7 +1,6 @@
 package sign
 
 import (
-	"io/ioutil"
 	"os"
 	"testing"
 	"time"
@@ -50,7 +49,7 @@ $ORIGIN example.org.
 @       IN      SOA     linode miek.miek.nl. ( 1282630060 4H 1H 7D 4H )
         IN      NS      linode
 `
-	if err := ioutil.WriteFile("db.apex-test.example.org", []byte(apex), 0644); err != nil {
+	if err := os.WriteFile("db.apex-test.example.org", []byte(apex), 0644); err != nil {
 		t.Fatal(err)
 	}
 	defer os.Remove("db.apex-test.example.org")