fix: Str helper namespace (overtrue#396)

Co-authored-by: 龙权 <[email protected]>

Author: lonquan

src/Middleware/OAuthAuthenticate.php

@@ -14,6 +14,7 @@
 use Closure;
 use http\Env\Request;
 use Illuminate\Support\Arr;
+use Illuminate\Support\Str;
 use Overtrue\LaravelWeChat\Events\WeChatUserAuthorized;
 
 /**