Slovakia IBAN parsing rules

Examples

    iex>  %IbanEx.Iban{
    ...>    country_code: "SK",
    ...>    check_digits: "31",
    ...>    bank_code: "1200",
    ...>    branch_code: nil,
    ...>    national_check: nil,
    ...>    account_number: "0000198742637541"
    ...>  }
    ...>  |> IbanEx.Country.SK.to_string()
    "SK 31 1200 0000198742637541"