chore: add basic tests for install task

test/mix/tasks/ash_postgres.install_test.exs

@@ -0,0 +1,13 @@
+defmodule Mix.Tasks.AshPostgres.InstallTest do
+  use ExUnit.Case
+
+  import Igniter.Test
+
+  # This is a simple test to ensure that the installation doesnt have
+  # any errors. We should add better tests here, though.
+  test "installation does not fail" do
+    test_project()
+    |> Igniter.compose_task("ash_postgres.install")
+    |> assert_creates("lib/test/repo.ex")
+  end
+end