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

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>

v2/internal/html/assetbundle.go

@@ -4,7 +4,7 @@ import (
 	"bytes"
 	"fmt"
 	"io"
-	"io/ioutil"
+	"os"
 	"path/filepath"
 	"strings"
 
@@ -189,7 +189,7 @@ func (a *AssetBundle) WriteToCFile(targetDir string) (string, error) {
 
 	// Save file
 	assetsFile := filepath.Join(targetDir, "assets.h")
-	err = ioutil.WriteFile(assetsFile, []byte(cdata.String()), 0600)
+	err = os.WriteFile(assetsFile, []byte(cdata.String()), 0600)
 	if err != nil {
 		return "", err
 	}