Bump version and changelog for v4.2.1

Author: darrenklein

CHANGELOG.md

@@ -1,5 +1,9 @@
 # Changelog
 
+## v4.2.1 - 2023-02-12
+
+- Fixes spec
+
 ## v4.2.0 - 2022-09-12
 
 - Add info on transaction failures

mix.exs

@@ -1,7 +1,7 @@
 defmodule ExAws.Dynamo.Mixfile do
   use Mix.Project
 
-  @version "4.2.0"
+  @version "4.2.1"
   @service "dynamo"
   @url "https://github.com/ex-aws/ex_aws_#{@service}"
   @name __MODULE__ |> Module.split() |> Enum.take(2) |> Enum.join(".")