fix: use ecto's uuid type under the hood

lib/ash/type/uuid.ex

@@ -8,24 +8,24 @@ defmodule Ash.Type.UUID do
   use Ash.Type
 
   @impl true
-  def storage_type, do: :binary_id
+  def storage_type, do: Ecto.UUID
 
   @impl true
   def cast_input(value, _) when is_binary(value) do
-    Ecto.Type.cast(:binary_id, String.trim(value))
+    Ecto.Type.cast(Ecto.UUID, String.trim(value))
   end
 
   def cast_input(value, _) do
-    Ecto.Type.cast(:binary_id, value)
+    Ecto.Type.cast(Ecto.UUID, value)
   end
 
   @impl true
   def cast_stored(value, _) do
-    Ecto.Type.load(:binary_id, value)
+    Ecto.Type.load(Ecto.UUID, value)
   end
 
   @impl true
   def dump_to_native(value, _) do
-    Ecto.Type.dump(:binary_id, value)
+    Ecto.Type.dump(Ecto.UUID, value)
   end
 end