This timezone has no DST changes.

"AOT" is what Timezone.Local.parse_tzfile gets from my /etc/localtime:

```
iex(1)> File.read!("/etc/localtime") |> Timezone.Local.parse_tzfile
{:ok, "AOT"}
```
The contents of my /etc/localtime are:

```
$ cat /etc/localtime   
TZifÄxL
       4AOTWATTZif2
                   ÿÿÿÿmI6ÿÿÿÿÄxL
                                 h
                                  LMTAOTWAT
WAT-1

```
 
Without this Timezone.Local.lookup will return nil and Date.local will not work. I'm not sure if parse_tzfile should be extracting WAT instead of AOT. Other libraries seem to consider both codes:
 - https://metacpan.org/source/BRAINTREE/Net-Braintree-0.1.0/perl5/DateTime/TimeZone/Africa/Luanda.pm
 - https://github.com/panthomakos/timezone/blob/master/data/Africa/Luanda.json