woocommerce_quantity_input_args min 0 - 1inc

<?php

function mym_woocommerce_quantity_input_args( $args, $product ) {
    $args['input_value'] = 0;   // Starting value
    $args['max_value'] = 100;   // Maximum value
    $args['min_value'] = 0;   // Minimum value
    $args['step']    = 1;   // Quantity steps
    return $args;
}
add_filter( 'woocommerce_quantity_input_args', 'mym_woocommerce_quantity_input_args', 10, 2 );