Refactor: move from io/ioutil to io and os package (#2234)

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 <zerjun@beatchain.co>

hack/utils/common.go

@@ -21,7 +21,6 @@ import (
 	"encoding/base64"
 	"fmt"
 	"io"
-	"io/ioutil"
 	"os"
 	"strings"
 
@@ -63,7 +62,7 @@ func GetChartSource(path string) (string, error) {
 		return "", err
 	}
 	defer os.Remove(packagedPath)
-	packaged, err := ioutil.ReadFile(packagedPath)
+	packaged, err := os.ReadFile(packagedPath)
 	if err != nil {
 		return "", err
 	}