Fixed missing account in MoveDistributionWorker (#11906)

app/workers/activitypub/move_distribution_worker.rb

@@ -8,6 +8,7 @@ class ActivityPub::MoveDistributionWorker
 
   def perform(migration_id)
     @migration = AccountMigration.find(migration_id)
+    @account   = @migration.account
 
     ActivityPub::DeliveryWorker.push_bulk(inboxes) do |inbox_url|
       [signed_payload, @account.id, inbox_url]