Fix unable to unpin follower-only posts (#17647)

app/presenters/status_relationships_presenter.rb

@@ -15,7 +15,7 @@ class StatusRelationshipsPresenter
       statuses            = statuses.compact
       status_ids          = statuses.flat_map { |s| [s.id, s.reblog_of_id] }.uniq.compact
       conversation_ids    = statuses.filter_map(&:conversation_id).uniq
-      pinnable_status_ids = statuses.map(&:proper).filter_map { |s| s.id if s.account_id == current_account_id && %w(public unlisted).include?(s.visibility) }
+      pinnable_status_ids = statuses.map(&:proper).filter_map { |s| s.id if s.account_id == current_account_id && %w(public unlisted private).include?(s.visibility) }
 
       @reblogs_map     = Status.reblogs_map(status_ids, current_account_id).merge(options[:reblogs_map] || {})
       @favourites_map  = Status.favourites_map(status_ids, current_account_id).merge(options[:favourites_map] || {})