Cron to Delete Revisions

wp-cron.php

<?php
// add filter to allow for new weekly schedule
add_filter( 'cron_schedules', 'my_weekly_cron' );

function my_weekly_cron( $schedules ) {
    // Adds once weekly to the existing schedules.
    $schedules['weekly'] = array(
        'interval' => 604800,
        'display' => __( 'Once Weekly' )
    );
    return $schedules;
}
add_action('my_revision_cron', 'my_revision_delete');

// set cron schedule
function my_revision_schedule() {
    if ( !wp_next_scheduled( 'my_revision_cron' ) ) {
        wp_schedule_event( time(), 'weekly', 'my_revision_cron');
    }
}
add_action('wp', 'my_revision_schedule');

// run deletion on revisions
function my_revision_delete() {

    // query revisions and get array of IDs
    $args = array(
        'fields'        => 'ids',
        'post_type'     => 'revision',
        'numberposts'   => -1
    );

    $revisions = get_posts($args);

    // loop through and delete each
    foreach ($revisions as $revision):

        wp_delete_post( $revision );

    endforeach;
}