Notification category matching bug

When using new post notification, email is not sent if the category has an &-sign.

This is because categories are saved to the database as string, and when matching, WordPress gives the category name with html entities, so the comparison is always invalid, and email is not sent.

I quickly fixed it by replacing html entities from category name before db query in es_notification_prepare @ db_notification.php, but better handling is recommended.

Just a FYI, if you want to fix it properly.

https://ww.wp.xz.cn/plugins/email-subscribers/