Specify default step of 1

Elixir 1.16 deprecates passing a range with negative step without
specifying the step.

Source:
https://hexdocs.pm/elixir/1.16.0-rc.0/String.html#slice/2

Author: jarroput

lib/bankster/iban.ex

@@ -243,7 +243,7 @@ defmodule Bankster.Iban do
   def bban(iban) do
     iban
     |> format_default()
-    |> String.slice(4..-1)
+    |> String.slice(4..-1//1)
   end
 
   @doc """
@@ -333,7 +333,7 @@ defmodule Bankster.Iban do
   @spec iban_violates_country_rule?(String.t()) :: boolean
   defp iban_violates_country_rule?(iban) do
     if iban_rule = get_in(@iban_rules, [country_code(iban), :rule]) do
-      !Regex.match?(iban_rule, String.slice(format_default(iban), 4..-1))
+      !Regex.match?(iban_rule, String.slice(format_default(iban), 4..-1//1))
     else
       false
     end
@@ -342,7 +342,10 @@ defmodule Bankster.Iban do
   @spec iban_violates_checksum?(String.t()) :: boolean
   defp iban_violates_checksum?(iban) do
     remainder =
-      for(<<c <- bban(iban) <> country_code(iban) <> "00">>, into: "", do: @replacements[<<c>>] || <<c>>)
+      for(<<c <- bban(iban) <> country_code(iban) <> "00">>,
+        into: "",
+        do: @replacements[<<c>>] || <<c>>
+      )
       |> String.to_integer()
       |> rem(97)
 

test/bankster/iban_test.exs

@@ -411,15 +411,15 @@ defmodule Bankster.Iban.IbanTest do
     for iban <- @unformated_ibans do
       assert(
         Bankster.Iban.bban(iban) ==
-          String.replace(iban, ~r/\s*/, "") |> String.upcase() |> String.slice(4..-1)
+          String.replace(iban, ~r/\s*/, "") |> String.upcase() |> String.slice(4..-1//1)
       )
     end
 
     # Formated IBANs
     for iban <- @formated_ibans do
       assert(
         Bankster.Iban.bban(iban) ==
-          String.replace(iban, ~r/\s*/, "") |> String.upcase() |> String.slice(4..-1)
+          String.replace(iban, ~r/\s*/, "") |> String.upcase() |> String.slice(4..-1//1)
       )
     end
   end