How To Enable WordPress Automatic Background Updates
Automatic background updates were introduced in WordPress 3.7 in an effort to promote better security, and to streamline the update experience overall. By default, only minor releases – such as for maintenance and security purposes – and translation file updates are enabled on most sites. In special cases, plugins and themes may be updated.
Add the following code in your wp-config.php
WordPress Core Update
add_filter( 'auto_update_plugin', '__return_true' );
add_filter( 'auto_update_theme', '__return_true' );
Disable Update notification Emails
add_filter( 'auto_core_update_send_email', '__return_false' );