replace deprecated method

listener/dns/listener.go

@@ -4,7 +4,7 @@ import (
 	"bytes"
 	"encoding/base64"
 	"errors"
-	"io/ioutil"
+	"io"
 	"net"
 	"net/http"
 	"strings"
@@ -164,7 +164,7 @@ func (l *dnsListener) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 			return
 		}
 
-		buf, err = ioutil.ReadAll(r.Body)
+		buf, err = io.ReadAll(r.Body)
 		if err != nil {
 			l.logger.Error(err)
 			http.Error(w, http.StatusText(http.StatusInternalServerError), http.StatusInternalServerError)