LORIS has incorrect access checks in issue_tracker

LORIS (Longitudinal Online Research and Imaging System) is a self-hosted web application that provides data- and project-management for neuroimaging research. In versions from 16.0.0 prior to 27.0.4 and from 28.0.0 prior to 28.0.2, the `issue_tracker` backend does not correctly verify edit access permissions, although the frontend restricts which issues a user may edit. An authenticated user can submit backend changes to issues outside the user's permitted edit scope. Deployments that no longer use Issue Tracker can disable the module to remove access to the endpoint. This issue is fixed in versions 27.0.4 and 28.0.2.