GHSA-vcc4-2c75-vc9v: Caddy: stripHTML template function bypass

Caddy's `stripHTML` template function (a tool that removes HTML tags from text) has a flaw where specially crafted malformed HTML like `<<>img src=x onerror=alert()>` can bypass the tag-removal logic and remain in the output. If this output is then displayed as HTML in a web page, it could allow XSS (cross-site scripting, where an attacker injects malicious code that runs in a user's browser).