feat: add surcharges model to Rate

CHANGELOG.md

@@ -2,6 +2,7 @@
 
 ## Next Release
 
+- Adds `surcharges` to `Rate` and a `Surcharge` model
 - Removes the deprecated, unusable `addCreditCard` function
   - Stripe has disabled the ability to pass plain credit card details over the wire and now requires using [Stripe.js/Elements/Checkout](https://support.stripe.com/questions/card-tokenization-restrictions-using-publishable-keys). Follow the [Decentralized (EasyPost-Manage Billing) Guide](https://docs.easypost.com/guides/get-started-with-forge/easypost-managed-billing-guide#referralcustomer-billing-management) for more details on the new flow to use.
   - Makes `referralCustomer.retrieveEasypostStripeApiKey` public to help facilitate adding credit cards using Stripe.js

lib/EasyPost/Rate.php

@@ -20,6 +20,7 @@
  * @property int $delivery_days
  * @property string $delivery_date
  * @property bool $delivery_date_guaranteed
+ * @property Surcharge[] $surcharges
  * @property string $created_at
  * @property string $updated_at
  */

lib/EasyPost/Surcharge.php

@@ -0,0 +1,17 @@
+<?php
+
+namespace EasyPost;
+
+/**
+ * @package EasyPost
+ * @property string $object
+ * @property string $type
+ * @property string $category
+ * @property string $amount
+ * @property string $list_amount
+ * @property string $retail_amount
+ * @property string $currency
+ */
+class Surcharge extends EasyPostObject
+{
+}

lib/EasyPost/Util/InternalUtil.php

@@ -30,6 +30,7 @@
 use EasyPost\Report;
 use EasyPost\ScanForm;
 use EasyPost\Shipment;
+use EasyPost\Surcharge;
 use EasyPost\TaxIdentifier;
 use EasyPost\Tracker;
 use EasyPost\TrackingDetail;
@@ -65,6 +66,7 @@
     'Shipment'              => Shipment::class,
     'ShipmentInvoiceReport' => Report::class,
     'ShipmentReport'        => Report::class,
+    'Surcharge'             => Surcharge::class,
     'TaxIdentifier'         => TaxIdentifier::class,
     'Tracker'               => Tracker::class,
     'TrackerReport'         => Report::class,

lib/easypost.php

@@ -82,6 +82,7 @@
 require_once(dirname(__FILE__) . '/EasyPost/Report.php');
 require_once(dirname(__FILE__) . '/EasyPost/ScanForm.php');
 require_once(dirname(__FILE__) . '/EasyPost/Shipment.php');
+require_once(dirname(__FILE__) . '/EasyPost/Surcharge.php');
 require_once(dirname(__FILE__) . '/EasyPost/TaxIdentifier.php');
 require_once(dirname(__FILE__) . '/EasyPost/Tracker.php');
 require_once(dirname(__FILE__) . '/EasyPost/TrackingDetail.php');