Replace .singular with .archive for event archives

/**
 * Remove .singular and replace with .archive for Event archives
 */
function use_archive_body_class_for_event_pages(array $classes) {
    $remove = false;

    if (in_array('events-archive', $classes) && in_array('singular', $classes)) {
        foreach ($classes as $key => $class) if ('singular' === $class) $remove = $key;
        if ($remove) unset($classes[$remove]);
        $classes[] = 'archive';
    }

    return $classes;
}

add_filter('body_class', 'use_archive_body_class_for_event_pages', 20);