It's too bad this app has been abandoned. Yet, there's a full docker install and I might have missed it or upstream might have changed their but I haven't seen a trace of a mention about the use of a "temporal server" as a requirement to run this.
Anyway, on the other hand, there's a cool work around for anyone running Hermes can run the Postiz Skill within one's Hermes instance. https://postiz.com/hermes
There also is the option to run it from a N8N Node https://www.npmjs.com/package/n8n-nodes-postiz
Enjoy!