Fix settings DSL migration

db/migrate/20230313105520_convert_settings_to_dsl.rb

@@ -2,6 +2,7 @@
 
 class ConvertSettingsToDsl < ActiveRecord::Migration[6.0]
   def up
-    Settings.where(category: 'Setting::NotificationSend').update_all(category: 'Setting')
+    Setting.where(category: 'Setting::NotificationSend').update_all(category: 'Setting') \
+      if column_exists?(:settings, :category)
   end
 end

lib/foreman_notification_send/version.rb

 # frozen_string_literal: true
 
 module ForemanNotificationSend
-  VERSION = '0.4.0'
+  VERSION = '0.4.1'
 end