disable external connections while testing with mimix

lib/elixir_ai/data/db_helpers.ex

@@ -83,3 +83,9 @@ defmodule ElixirAi.Data.DbHelpers do
     {positional_sql, ordered_values}
   end
 end
+
+defmodule ElixirAi.Repo do
+  use Ecto.Repo,
+    otp_app: :elixir_ai,
+    adapter: Ecto.Adapters.Postgres
+end