make form batch proc

admin/app/admin/onboarding.rb

@@ -10,9 +10,9 @@ ActiveAdmin.register JamRuby::User, :as => 'CurrentlyOnboarding' do
   config.clear_action_items!
   batch_action :destroy, false
 
-  batch_action :onboarder, form: {
+  batch_action :onboarder, form: -> { {
                         support_consultant: (User.where(is_onboarder: true).includes(:onboarding_users).map {|user| ["#{user.name} (#{user.onboarding_users.length})", user.id]}).to_a.unshift(['Unassign', ''])
-                    } do |ids, inputs|
+                    } } do |ids, inputs|
     onboarder = inputs[:support_consultant]
     if onboarder.blank?
       onboarder = nil