feat: add guest cart payment methods endpoint

Author: ahinkle

src/Api/GuestCarts.php

@@ -98,4 +98,14 @@ public function shippingInformation($cartId, $body = [])
     {
         return $this->post('/guest-carts/'.$cartId.'/shipping-information', $body);
     }
+
+    /**
+     * List available payment methods for a specified shopping cart. This call returns an array of objects, but detailed information about each object’s attributes might not be included.
+     *
+     * @return array
+     */
+    public function paymentMethods($cartId)
+    {
+        return $this->get('/guest-carts/'.$cartId.'/payment-methods');
+    }
 }

tests/Api/GuestCartsTest.php

@@ -108,4 +108,17 @@ public function test_can_call_guest_carts_shipping_information()
 
         $this->assertTrue($api->ok());
     }
+
+    public function test_can_call_guest_carts_payment_methods()
+    {
+        Http::fake([
+            '*rest/all/V1/guest-carts/foo/payment-methods' => Http::response([], 200),
+        ]);
+
+        $magento = new Magento();
+
+        $api = $magento->api('guestCarts')->paymentMethods('foo');
+
+        $this->assertTrue($api->ok());
+    }
 }