`Timex.from_now` rounds up to minute after 45 seconds

### Steps to reproduce

```elixir
now = ~U[2022-12-15 03:59:00.529722Z]
expires_at = ~U[2022-12-15 03:59:45.529722Z]
Timex.from_now(expires_at, now)
# => "in 45 seconds"

now = ~U[2022-12-15 03:59:00.529722Z]
expires_at = ~U[2022-12-15 03:59:46.529722Z]
Timex.from_now(expires_at, now)
# => "in 1 minute"
```

### Description of issue

- What are the expected results?
- Returns `in 46 seconds`

- If you are certain this is a bug in Timex, do you have references I
can use to check the algorithm/logic against? For instance, a well-established
date/time library in another language, a paper, test suite, etc. It is by no
means a requirement, but is immensely helpful in fixing bugs, and provides me
extra data to use when building out the test suite
- [cldr_date_times](https://github.com/elixir-cldr/cldr_dates_times) works as expected