Added new countries

lib/iban_ex/country/so.ex

@@ -0,0 +1,43 @@
+defmodule IbanEx.Country.SO do
+  @moduledoc """
+  Somalia IBAN parsing rules
+
+  ## Examples
+
+  ```elixir
+      iex>  %IbanEx.Iban{
+      ...>    country_code: "SO",
+      ...>    check_digits: "21",
+      ...>    bank_code: "1000",
+      ...>    branch_code: "001",
+      ...>    national_check: nil,
+      ...>    account_number: "001000100141"
+      ...>  }
+      ...>  |> IbanEx.Country.SO.to_string()
+      "SO 21 1000 001 001000100141"
+  ```
+  """
+
+  @size 23
+  @rule ~r/^(?<bank_code>[0-9]{4})(?<branch_code>[0-9]{3})(?<account_number>[0-9]{12})$/i
+
+  use IbanEx.Country.Template
+
+  @impl IbanEx.Country.Template
+  @spec to_string(Iban.t()) :: binary()
+  @spec to_string(Iban.t(), binary()) :: binary()
+  def to_string(
+        %Iban{
+          country_code: country_code,
+          check_digits: check_digits,
+          bank_code: bank_code,
+          branch_code: branch_code,
+          account_number: account_number
+        } = _iban,
+        joiner \\ " "
+      ) do
+    [country_code, check_digits, bank_code, branch_code, account_number]
+    |> Enum.join(joiner)
+  end
+end
+