chore: bump version to 0.4.0

Author: fahchen

README.md

@@ -25,7 +25,7 @@ Add to your `mix.exs`:
 ```elixir
 def deps do
   [
-    {:dprint_markdown_formatter, "~> 0.1.0"}
+    {:dprint_markdown_formatter, "~> 0.4.0"}
   ]
 end
 ```

llms.txt

@@ -21,7 +21,7 @@ Add to `mix.exs`:
 ```elixir
 def deps do
   [
-    {:dprint_markdown_formatter, "~> 0.1.0"}
+    {:dprint_markdown_formatter, "~> 0.4.0"}
   ]
 end
 ```

mix.exs

@@ -1,7 +1,7 @@
 defmodule DprintMarkdownFormatter.MixProject do
   use Mix.Project
 
-  @version "0.3.0"
+  @version "0.4.0"
   @source_url "https://github.com/fahchen/dprint_markdown_formatter"
 
   def project do