1. Download the file from the merge request and put it into the folder /usr/share/proxmox-acme/dnsapi/
2. add following to the file /usr/share/proxmox-acme/dns-challenge-schema.json
Code:
"hetznercloud": {},
I put i directly after the hetzer entry...
3. Reboot Proxmox. Just rebooting the pveproxy didn't work for me
4. After this you can configure hetznercloud from the UI
But as mentioned: no recommendation... I don't know what it will break in the future. For the moment it work just fine for me