Change version of PO3 server

[seetee]

The Docker-file includes the URL for the version of the PO3 server on the Curseforge CDN. But I do not seem to manage to update that URL. Neither the link of the download file-button on Curseforge nor a locally downloaded file seem to work. How do I acquire a direct link to the CDN?

I am aware that this is only tangentially related to this project, but perhaps it could be worth a line in the README.md?

Thank you for a great project!