feat: replace github.com/pkg/errors to errors

Signed-off-by: haoyun <yun.hao@daocloud.io>
Co-authored-by: zounengren <zouyee1989@gmail.com>

diff/stream.go

@@ -18,6 +18,7 @@ package diff
 
 import (
 	"context"
+	"errors"
 	"io"
 	"os"
 
@@ -25,7 +26,6 @@ import (
 	"github.com/containerd/containerd/images"
 	"github.com/gogo/protobuf/types"
 	ocispec "github.com/opencontainers/image-spec/specs-go/v1"
-	"github.com/pkg/errors"
 )
 
 var (