Add the default OBS_FRONTEND_WORKERS: 4 to demonstrate its existence

Signed-off-by: Andrej Shadura <andrew.shadura@collabora.co.uk>

docker-compose.yml

@@ -51,6 +51,7 @@ services:
       DB_USER: obs-api
       DB_PASSWORD: someobs
       OBS_BACKEND_HOST: obs-server
+      OBS_FRONTEND_WORKERS: 4
     networks:
       - obs
     ports: