I tend to receive an error while the version in the `docker-compose.yml` is `21.05.2` as it seems this version doesn't exist.  To fix it I changed it to `solidnerd/bookstack:latest` but I don't think this is a solid fix 😅 so maybe you can provide a better fix there. -- Edit -- Okay, I just saw that #259 was some fix for continous integration, so I'm not sure what I'm doing wrong here.