maintenance: prune approvers monthly instead of weekly.

* Move approver pruning from a weekly task to a monthly task.
* Move weekly maintenance tasks from Wednesdays at 1:30am to Sundays at
  midnight (UTC).

app/logical/danbooru_maintenance.rb

@@ -23,10 +23,13 @@ module DanbooruMaintenance
 
   def weekly
     safely { UserPasswordResetNonce.prune! }
-    safely { ApproverPruner.prune! }
     safely { TagRelationshipRetirementService.find_and_retire! }
   end
 
+  def monthly
+    safely { ApproverPruner.prune! }
+  end
+
   def regenerate_post_counts!
     updated_tags = Tag.regenerate_post_counts!
     updated_tags.each do |tag|

config/schedule.rb

@@ -3,14 +3,18 @@ env "RAILS_LOG_TO_STDOUT", "true"
 
 set :output, "log/whenever.log"
 
-every 1.hour do
+every :hour do
   rake "maintenance:hourly"
 end
 
-every 1.day do
+every :day do
   rake "maintenance:daily"
 end
 
-every 1.week, :at => "1:30 am" do
+every :sunday do
   rake "maintenance:weekly"
 end
+
+every :month do
+  rake "maintenance:monthly"
+end

lib/tasks/maintenance.rake

@@ -15,4 +15,9 @@ namespace :maintenance do
   task weekly: :environment do
     DanbooruMaintenance.weekly
   end
+
+  desc "Run monthly maintenance jobs"
+  task monthly: :environment do
+    DanbooruMaintenance.monthly
+  end
 end