Tunisia IBAN parsing rules

Examples

    iex>  %IbanEx.Iban{
    ...>    country_code: "TN",
    ...>    check_digits: "59",
    ...>    bank_code: "10",
    ...>    branch_code: "006",
    ...>    account_number: "0351835984788",
    ...>    national_check: "31"
    ...>  }
    ...>  |> IbanEx.Country.TN.to_string()
    "TN 59 10 006 0351835984788 31"