Invalid timestamp is being accepted by method parse_from_rfc3339

[kulsarve]

parse_from_rfc3339 method accepts the following timestamp "3000-01-01T10:00:60.000Z" which represents January 1st, 3000 at 10:00:60 AM UTC which is invalid, still it's being accepted.

Please refer to following example where above is observed: https://gist.github.com/rust-play/cc721b90f077459c9db8a0f142dc1d17

[djc]

There is limited support for leap seconds (but, as far as I remember, no list of known leap seconds), so that's why :60 gets accepted.