ulozto: Fix handling of root paths with leading / trailing slashes.

This fixes #7796

backend/ulozto/ulozto.go

@@ -121,6 +121,9 @@ func NewFs(ctx context.Context, name, root string, m configmap.Mapper) (fs.Fs, e
 		return nil, err
 	}
 
+	// Strip leading and trailing slashes, see https://github.com/rclone/rclone/issues/7796 for details.
+	root = strings.Trim(root, "/")
+
 	client := fshttp.NewClient(ctx)
 
 	f := &Fs{