tests: fix unit tests.

* Move old post archive tests to post version tests.

* Fix pool tests that assumed that multiple edits by the same user
  weren't merged.

* Fix references to `is_active` and `notes` on artist model.

test/unit/post_approval_test.rb

@@ -3,7 +3,7 @@ require 'test_helper'
 class PostApprovalTest < ActiveSupport::TestCase
   context "a pending post" do
     setup do
-      @user = FactoryBot.create(:user)
+      @user = FactoryBot.create(:user, created_at: 2.weeks.ago)
       CurrentUser.user = @user
       CurrentUser.ip_addr = "127.0.0.1"