Apply Layout/LineLength rubocop rule

Note we're excluding a few files:

* Configuration files that weren't generated by us
* Migration files that weren't generated by us
* The Gemfile, since it includes an important comment that must be on
  the same line as the gem declaration
* The Budget::Stats class, since the heading statistics are a mess and
  having shorter lines would require a lot of refactoring

app/components/relationable/related_list_component.rb

@@ -13,6 +13,8 @@ class Relationable::RelatedListComponent < ApplicationComponent
   private
 
     def related_contents
-      @related_contents ||= Kaminari.paginate_array(relationable.relationed_contents).page(params[:page]).per(5)
+      @related_contents ||= Kaminari.paginate_array(relationable.relationed_contents)
+                                    .page(params[:page])
+                                    .per(5)
     end
 end