添加PayClientEnum

src/Pay/Enum/PayClientEnum.php

+<?php
+namespace Hdll\Services\Pay\Enum;
+
+class PayClientEnum 
+{
+    const BUYER_MINI_PROGRAM = 1;//买家小程序
+    const SELLER_MINI_PROGRAM = 2;//卖家小程序
+    const SELLER_MP = 3;//卖家公众号
+
+    
+}
\ No newline at end of file