jellyfin: update for proper use of Intel QSV.

jellyfin/docker-compose.yml

@@ -3,6 +3,10 @@ services:
     image: nyanmisaka/jellyfin:latest
     container_name: jellyfin
     network_mode: 'host'
+    group_add:
+      # needs mapping from localhost, i.e. `getent group render | cut -d: -f3`.
+      # also probably needs manual `groupadd -g 993 render` inside.
+      - '993'
     volumes:
       - /opt/jellyfin:/config
       - jellyfin-cache:/cache