XDG_SESSION_ID not set from uwsm app

The variable ends up in `/run/user/1000/uwsm/env_session.conf`: ``` XDG_SEAT=seat0 XDG_SESSION_ID=1 XDG_VTNR=1 ``` And I've verified that it's also available to the compositor: when I start a terminal directly from the compositor, the variable is set. But when I start a terminal via `uwsm app` or `uwsm-app`, the variable is not set, but this should be the case according to the README. system info: ``` uwsm 0.26.0+git.12.d022915 (uwsm-git AUR package) Arch Linux ```