Remove gogoproto.stdtime

This commit removes gogoproto.stdtime, since it is not supported by
Google's official toolchain
(see https://github.com/containerd/containerd/issues/6564).

Signed-off-by: Kazuyoshi Kato <katokazu@amazon.com>

runtime/v2/runc/v2/service.go

@@ -23,6 +23,7 @@ import (
 	"context"
 
 	"github.com/containerd/containerd/pkg/shutdown"
+	"github.com/containerd/containerd/protobuf"
 	"github.com/containerd/containerd/runtime/v2/runc/manager"
 	"github.com/containerd/containerd/runtime/v2/runc/task"
 	"github.com/containerd/containerd/runtime/v2/shim"
@@ -45,7 +46,7 @@ func (stm *shimTaskManager) Cleanup(ctx context.Context) (*shimapi.DeleteRespons
 	return &shimapi.DeleteResponse{
 		Pid:        uint32(ss.Pid),
 		ExitStatus: uint32(ss.ExitStatus),
-		ExitedAt:   ss.ExitedAt,
+		ExitedAt:   protobuf.ToTimestamp(ss.ExitedAt),
 	}, nil
 }