float64_be
64 bit big endian float
iex> defmodule Struct do
...> use BinStruct
...> field :value, :float64_be
...> end
...>
...> Struct.new(value: 1.0)
...> |> Struct.dump_binary()
...> |> Struct.parse()
...> |> then(fn {:ok, struct, _rest } -> struct end)
...> |> Struct.decode()
%{ value: 1.0 }