- Create a user A with access rights to Project set as 'User'
- As user A, add a follower to a task
An AccessError is raised.
It happens because `allowed_user_ids` has the group
`project.group_project_manager`.
Since a Project User is allowed to set followers on a task, it is
legitimate to set the appropriate portal user as allowed.
opw-2369674
closesodoo/odoo#60725
X-original-commit: 5ee045b2532ce97094dea2fe6b5e354585d67691
Signed-off-by: Nicolas Martinelli (nim) <nim@odoo.com>