Reduce the strength requirement for woocommerce registration password.

functions.php

<?php
/*
* Reduce the strength requirement for woocommerce registration password.
* Strength Settings:
* 0 = Nothing = Anything
* 1 = Weak
* 2 = Medium
* 3 = Strong (default)
*/

add_filter( 'woocommerce_min_password_strength', 'mt_woocommerce_password_strength', 10 );
function mt_woocommerce_password_strength() {
return 2; //2 represent medium strength password
}