Custom checkbox in WooCommerce

I want to customize the HTML code for the subscription checkbox in WooCommerce.
Now the code looks like this:

private function getSubscriptionField($inputName, $checked, $labelString) {
    return '<p class="form-row">
      <label class="woocommerce-form__label woocommerce-form__label-for-checkbox checkbox">
      <input type="checkbox" class="woocommerce-form__input woocommerce-form__input-checkbox input-checkbox" name="' . $this->wp->escAttr($inputName) . '" id="' . $this->wp->escAttr($inputName) . '" ' . ($checked ? 'checked' : '') . ' />
        <span class="woocommerce-terms-and-conditions-checkbox-text">' . $this->wp->escHtml($labelString) . '</label>
    </p>';
  }

I need it to be that way since I use Bootstrap 4

private function getSubscriptionField($inputName, $checked, $labelString)
  {
    return '<div class="form-group form-check">
      <input type="checkbox" class="woocommerce-form__input woocommerce-form__input-checkbox input-checkbox" name="' . $this->wp->escAttr($inputName) . '" id="' . $this->wp->escAttr($inputName) . '" ' . ($checked ? 'checked' : '') . ' />
      <label for="' . $this->wp->escAttr($inputName) . '" class="woocommerce-form__label woocommerce-form__label-for-checkbox checkbox">
        <span class="woocommerce-terms-and-conditions-checkbox-text">' . $this->wp->escHtml($labelString) . '</label>
    </div>';
  }

How can I do this without changing the code in the file /plugins/mailpoet/lib/WooCommerce/Subscription.php ?