preg_replace unicode 的兼容问题

[springjk]

我用的环境

PHP 版本：5.6.11
overtrue/wechat 版本：3.1

在一些无法支持修改环境的虚拟主机上正则\P不被支持

Warning: preg_replace(): Compilation failed: support for \P, \p, and \X has not been compiled at offset 1 in /var/www/virtual/crgb/home/wwwroot/wp-content/plugins/wechat-broadcast/vendor/overtrue/wechat/src/Core/Http.php on line 280

Catchable fatal error: Argument 1 passed to EasyWeChat\Core\AbstractAPI::checkAndThrow() must be of the type array, boolean given, called in ***/home/wwwroot/wp-content/plugins/wechat-broadcast/vendor/overtrue/wechat/src/Core/AbstractAPI.php on line 135 and defined in ***/home/wwwroot/wp-content/plugins/wechat-broadcast/vendor/overtrue/wechat/src/Core/AbstractAPI.php on line 228

[springjk]

因为在虚拟主机上无法进行扩展安装和版本升级，故 fuckTheWeChatInvalidJSON 函数中的正则不被支持，我参考 正则文档 修改提交了 pull-516，能否合并这个兼容处理。

[springjk]

Merged #519