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

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

services/diff/service.go

@@ -18,11 +18,11 @@ package diff
 
 import (
 	"context"
+	"errors"
 
 	diffapi "github.com/containerd/containerd/api/services/diff/v1"
 	"github.com/containerd/containerd/plugin"
 	"github.com/containerd/containerd/services"
-	"github.com/pkg/errors"
 	"google.golang.org/grpc"
 )