run ssh-chat and matterbridge under nobody user

docker-compose.yaml

@@ -4,6 +4,7 @@ services:
     restart: unless-stopped
     ports:
       - 2022:2022
+    user: nobody
     secrets:
       - chatkey
     volumes:
@@ -14,6 +15,7 @@ services:
   matterbridge:
     build: https://gitea.demb.uk/third-party-mirrors/matterbridge.git#v1.26.0
     restart: unless-stopped
+    user: nobody
     volumes:
       - ./matterbridge/matterbridge.toml:/etc/matterbridge/matterbridge.toml:ro
     environment: