Rename Size_ to Size

Previouslty "Size" was reserved by protoc-gen-gogoctrd and user-generated
"Size" was automatically renamed to "Size_" to avoid conflicts.

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

container_checkpoint_opts.go

@@ -73,7 +73,7 @@ func WithCheckpointTask(ctx context.Context, client *Client, c *containers.Conta
 		platformSpec := platforms.DefaultSpec()
 		index.Manifests = append(index.Manifests, imagespec.Descriptor{
 			MediaType:   d.MediaType,
-			Size:        d.Size_,
+			Size:        d.Size,
 			Digest:      digest.Digest(d.Digest),
 			Platform:    &platformSpec,
 			Annotations: d.Annotations,