`security.txt` expires at `2024-12-31T23:59:00.000Z`

[viceice]

Describe the proposed change(s).

https://github.com/renovatebot/renovatebot.github.io/blob/c0b244dd36fb1e1b6a7afd2234af5f1f7542df73/src/security.txt#L2

needs an update before expirery