work_items.relations calls non-existent API endpoint #16
Description
The WorkItemRelations class in plane/api/work_items/relations.py calls a relation endpoint /work-items/{work_item_id}/relations that doesn't actually exist in Plane right now.
There is an issue, makeplane/plane#6236, that is requesting to add an official relation management API.
It seems like this should be removed, or the above issue should be prioritized and working endpoints should be added.