Merge branch '4.0' of github.com:top-think/think-orm into 4.0

Author: liu21st

src/Model.php

@@ -20,6 +20,7 @@
 use think\contract\Jsonable;
 use think\db\BaseQuery as Query;
 use think\db\Express;
+use think\exception\InvalidArgumentException;
 use think\exception\ValidateException;
 use think\model\Collection;
 use think\model\contract\Modelable;