many() relation is not displayed in admin list

[alex-rudakov]

ERRORS:
<class 'main.admin.RabbitHujabitAdmin'>: (admin.E108) The value of 'list_display[5]' refers to 'get_owners', which is not a callable, an attribute of 'RabbitHujabitAdmin', or an attribute or method on 'main.RabbitHujabit'.