Allow for alternative erlang solutions in `captains-log`

Given that the main focus of this exercise is to use erlang libaries, it feels strange to receive analyzer errors for the following two solutions:

`random_ship_registry/0` (prompts to use `Enum.random/1`):
```elixir
def random_ship_registry_number() do
digits = :rand.uniform(9000) + 999

"NCC-#{digits}"
end
```

`format_stardate/1` (prompts to use `:io_lib.format("~.1f", [stardate]) |> to_string()`):
```elixir
def format_stardate(stardate) do
stardate
|> :erlang.float_to_binary([{:decimals, 1}])
end
```

Would it make sense to have the analyzer allow one or both of these alternate solutions, since they are still using erlang?