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

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

services/content/service.go

@@ -17,11 +17,12 @@
 package content
 
 import (
+	"errors"
+
 	"github.com/containerd/containerd/content"
 	"github.com/containerd/containerd/plugin"
 	"github.com/containerd/containerd/services"
 	"github.com/containerd/containerd/services/content/contentserver"
-	"github.com/pkg/errors"
 )
 
 func init() {