Stream.new with NaiveDateTime with microseconds fails

[dbernheisel]

Looks like when microseconds are present, it cannot generate a stream of occurrences.

iex> Excal.Recurrence.Stream.new("FREQ=WEEKLY;BYDAY=MO,WE,FR", NaiveDateTime.utc_now())
{:error, :invalid_dtstart}

iex> Excal.Recurrence.Stream.new("FREQ=WEEKLY;BYDAY=MO,WE,FR", NaiveDateTime.truncate(NaiveDateTime.utc_now(), :second))
{:ok, #Function<54.48559900/2 in Stream.resource/3>}

This seems to be coming from the NIF where it's checking for null time