refactor: move from io/ioutil to io and os package

The io/ioutil package has been deprecated as of Go 1.16, see
https://golang.org/doc/go1.16#ioutil. This commit replaces the existing
io/ioutil functions with their new definitions in io and os packages.

Signed-off-by: Eng Zer Jun <engzerjun@gmail.com>

weed/storage/needle/needle_read_write_test.go

@@ -1,7 +1,6 @@
 package needle
 
 import (
-	"io/ioutil"
 	"os"
 	"testing"
 
@@ -31,7 +30,7 @@ func TestAppend(t *testing.T) {
 		Padding:      nil,                 // Padding    []byte `comment:"Aligned to 8 bytes"`
 	}
 
-	tempFile, err := ioutil.TempFile("", ".dat")
+	tempFile, err := os.CreateTemp("", ".dat")
 	if err != nil {
 		t.Errorf("Fail TempFile. %v", err)
 		return