When the tasks were migrated from belonging directly to a bucket to only belonging to a view, I forgot to add the view in that migration, resulting in task buckets where the view was 0. These entries were not deleted when a task was moved between buckets, but the new task bucket relation nevertheless inserted. This resulted in tasks showing up multiple times on the kanban board.
This change adds a new migration which adds the correct project view id (as derived from the bucket) and fixes the old migration as well.
Resolves https://community.vikunja.io/t/no-longer-able-to-properly-move-tasks-between-kanban-columns/2175
