Add WooCommerce up- and download mime type for DMG files

functions.part.php

// allow DMG file upload for WC
add_filter('upload_mimes', 'ith__allow_dmg_upload');
function ith__allow_dmg_upload($mime_types){
    $mime_types['dmg'] = 'application/x-apple-diskimage';
    return $mime_types;
}

// allow DMG file download for WC
add_filter( 'woocommerce_file_download_allowed_mime_types', 'ith__add_dmg_mime_type' );
function ith__add_dmg_mime_type( $mime_types ){
    $mime_types[] = 'application/x-apple-diskimage';
    return $mime_types;
}