Place in the functions.php file:
$func = function ($a) {
global $wp_version;
return (object) array(
'last_checked' => time(),
'version_checked' => $wp_version,
);
};
add_filter('pre_site_transient_update_core', $func);
add_filter('pre_site_transient_update_plugins', $func);
add_filter('pre_site_transient_update_themes', $func);