Move expires_at to timestamp data

lib/gitlab/hook_data/base_builder.rb

@@ -24,7 +24,8 @@ module Gitlab
       def timestamps_data
         {
           created_at: object.created_at&.xmlschema,
-          updated_at: object.updated_at&.xmlschema
+          updated_at: object.updated_at&.xmlschema,
+          expires_at: object.expires_at&.xmlschema
         }
       end
 

lib/gitlab/hook_data/group_member_builder.rb

@@ -41,8 +41,7 @@ module Gitlab
           user_name: group_member.user.name,
           user_email: group_member.user.email,
           user_id: group_member.user.id,
-          group_access: group_member.human_access,
-          expires_at: group_member.expires_at&.xmlschema
+          group_access: group_member.human_access
         }
       end