refactor: move from io/ioutil to io and os package (#17109)

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>

Co-authored-by: techknowlogick <techknowlogick@gitea.io>

modules/git/blob_test.go

@@ -6,7 +6,7 @@
 package git
 
 import (
-	"io/ioutil"
+	"io"
 	"path/filepath"
 	"testing"
 
@@ -30,7 +30,7 @@ func TestBlob_Data(t *testing.T) {
 	assert.NoError(t, err)
 	require.NotNil(t, r)
 
-	data, err := ioutil.ReadAll(r)
+	data, err := io.ReadAll(r)
 	assert.NoError(t, r.Close())
 
 	assert.NoError(t, err)
@@ -55,7 +55,7 @@ func Benchmark_Blob_Data(b *testing.B) {
 		if err != nil {
 			b.Fatal(err)
 		}
-		ioutil.ReadAll(r)
+		io.ReadAll(r)
 		_ = r.Close()
 	}
 }