GHSA-JRC6-FMHW-FPQ2 Kimai: Username enumeration via timing on X-AUTH-USER

Details src/API/Authentication/TokenAuthenticator.php calls loadUserByIdentifier first and only invokes the password hasher argon2id when a user is returned. When the username does not exist, the request returns roughly 25 ms faster than when it does. The response body is the same in both cases...