gcs: fix directory marker code #3453

Use Update to upload the directory markers

backend/googlecloudstorage/googlecloudstorage.go

@@ -897,7 +897,8 @@ func (f *Fs) createDirectoryMarker(ctx context.Context, bucket, dir string) erro
 
 	// Object to be uploaded
 	o := &Object{
-		fs: f,
+		fs:      f,
+		modTime: time.Now(),
 	}
 
 	for {
@@ -917,7 +918,7 @@ func (f *Fs) createDirectoryMarker(ctx context.Context, bucket, dir string) erro
 		// Upload it if not
 		fs.Debugf(o, "Creating directory marker")
 		content := io.Reader(strings.NewReader(""))
-		_, err = f.Put(ctx, content, o)
+		err = o.Update(ctx, content, o)
 		if err != nil {
 			return fmt.Errorf("creating directory marker failed: %w", err)
 		}