Anubis vulnerable to possible XSS via redir parameter when using subrequest auth mode

Anubis is a Web AI Firewall Utility that challenges users' connections in order to protect upstream resources from scraper bots. Prior to version 1.23.0, when using subrequest authentication, Anubis did not perform validation of the redirect URL and redirects user to any URL scheme. While most modern browsers do not allow a redirect to `javascript:` URLs, it could still trigger dangerous behavior in some cases. Anybody with a subrequest authentication may be affected. Version 1.23.0 contains a fix for the issue.