The post-admin-menu widget has been “removed” recently in favor of a glimmer component here admin-post-menu.gjs.
https://github.com/discourse/discourse/pull/23650
The proper way to add a button is to use the addPostAdminMenuButton API instead:
api.addPostAdminMenuButton((name, attrs) => {
return {
action: (post) => {
const ajaxParams = {
type: 'POST',
data: { post_id: post.id }
};
ajax("/reset_bump", ajaxParams).catch(popupAjaxError);
},
icon: 'calendar-times',
className: 'reset-bump',
label: 'reset_bump.button_label',
};
});