Fixed test cases (#7643)

Author: limingxinleo

src/Fluent.php

@@ -22,6 +22,7 @@
 use Hyperf\Support\Traits\InteractsWithData;
 use IteratorAggregate;
 use JsonSerializable;
+use Stringable;
 use Traversable;
 
 use function Hyperf\Collection\data_get;
@@ -37,7 +38,7 @@
  * @implements \Hyperf\Contract\Arrayable<TKey, TValue>
  * @implements ArrayAccess<TKey, TValue>
  */
-class Fluent implements ArrayAccess, Arrayable, IteratorAggregate, Jsonable, JsonSerializable
+class Fluent implements Stringable, ArrayAccess, Arrayable, IteratorAggregate, Jsonable, JsonSerializable
 {
     use InteractsWithData;
     use Macroable{

src/MessageBag.php

@@ -20,10 +20,11 @@
 use Hyperf\Contract\MessageProvider;
 use Hyperf\Stringable\Str;
 use JsonSerializable;
+use Stringable;
 
 use function Hyperf\Collection\collect;
 
-class MessageBag implements Arrayable, Countable, Jsonable, JsonSerializable, MessageBagContract, MessageProvider
+class MessageBag implements Stringable, Arrayable, Countable, Jsonable, JsonSerializable, MessageBagContract, MessageProvider
 {
     /**
      * All the registered messages.