Calling Interval.new on DateTimes, changes the interval to use NaiveDateTime

[gaiabeatrice]

Steps to reproduce

The following code snippet:

from = ~U[2021-01-07 00:00:00.000000Z]
until = ~U[2021-03-07 00:00:00.000000Z]

Timex.Interval.new(from: from, until: until)

returns:

%Timex.Interval{
  from: ~N[2021-01-07 00:00:00.000000],
  left_open: false,
  right_open: true,
  step: [days: 1],
  until: ~N[2021-03-07 00:00:00.000000]
}

Description of issue

I would expect the result to keep the same type as the input ones, and not implicitly convert them to NaiveDateTime.