cart.php

<?php
  if ( $_product->is_sold_individually() ) {
    $product_quantity = sprintf( '1 <input type="hidden" name="cart[%s][qty]" value="1" />', $cart_item_key );
  } else {
    $product_quantity = woocommerce_quantity_input( array(
      'input_name'   => "cart[{$cart_item_key}][qty]",
      'input_value'  => $cart_item['quantity'],
      'max_value'    => $_product->get_max_purchase_quantity(),
      'min_value'    => '0',
      'product_name' => $_product->get_name(),
    ), $_product, false );
  }
  echo apply_filters( 'woocommerce_cart_item_quantity', $product_quantity, $cart_item_key, $cart_item ); // PHPCS: XSS ok.
?>