Import demo data

I have wordpress theme and need to make the importer work with my demos, but i have issue on it , so I can’t upload my theme to themefoest marketplac, please advice and check the following error

REQUIRED: wp_get_http() found in the file functions/importer/wordpress-importer.php. Deprecated since version 4.4. Use WP_Http instead.
Line 905: $headers = wp_get_http( $url, $upload[‘file’] );