add authorization checks

app/controllers/submissions_unarchive_controller.rb

@@ -4,6 +4,8 @@ class SubmissionsUnarchiveController < ApplicationController
   load_and_authorize_resource :submission
 
   def create
+    authorize!(:update, @submission)
+
     @submission.update!(archived_at: nil)
 
     redirect_to submission_path(@submission), notice: I18n.t('submission_has_been_unarchived')