Update to go1.16

pkg/middlewares/auth/forward.go

@@ -4,7 +4,7 @@ import (
 	"context"
 	"errors"
 	"fmt"
-	"io/ioutil"
+	"io"
 	"net"
 	"net/http"
 	"regexp"
@@ -126,7 +126,7 @@ func (fa *forwardAuth) ServeHTTP(rw http.ResponseWriter, req *http.Request) {
 		return
 	}
 
-	body, readError := ioutil.ReadAll(forwardResponse.Body)
+	body, readError := io.ReadAll(forwardResponse.Body)
 	if readError != nil {
 		logMessage := fmt.Sprintf("Error reading body %s. Cause: %s", fa.address, readError)
 		logger.Debug(logMessage)