DEV: Compatibility with Discourse on Rails 6.1 (#14)

Related to discourse/discourse#12688.

Rails 6.1 changes the initializer of `ActionView::Base` to require 3 arguments. Instead of creating the instance ourselves, we can use the [`ActionView::Base.with_view_paths`](https://github.com/rails/rails/blob/c5929d5eb55b749bc124b3ccc2d79323d015701f/actionview/lib/action_view/base.rb#L229-L231) method that gives us an instance with whatever view paths we need. The `with_view_paths` method is available in Rails 6.0.3.5 (Discourse's current Rails version), so this change is backward compatible.

app/jobs/yearly_review.rb

@@ -22,7 +22,7 @@ def execute(args)
         return if Topic.where(user: Discourse.system_user, title: title).exists?
       end
 
-      view = ActionView::Base.new(ActionView::LookupContext.new(ActionController::Base.view_paths), {})
+      view = ActionView::Base.with_view_paths(ActionController::Base.view_paths)
       view.class_eval do
         include YearlyReviewHelper
         def compiled_method_container