LinuxServer Changes:
Install unrar from linuxserver repo.
mylar3 Changes:
webserve: introduce /prometheus_metrics with queue metrics
This serves up the current queue status in the Prometheus exposition
format[0]. This allows the current status of the queues to be scraped
by Prometheus, allowing for integration into people's home monitoring
systems.
[0] https://github.com/prometheus/docs/blob/main/content/docs/instrumenting/exposition_formats.md