Unable to purge key/regex via API (Caddy)

[Ghostavio]

Purging all through /flush works but trying to purge keys with ids or regex doesn't.

Basically the same issue as #658

[Ghostavio]

Also since the API was moved to Caddy's admin api I can't access it anymore from within a Docker container if Caddy is running on the host machine. I believe it would be helpful to allow the user to decide where to run Souin api without it being necessarily attatched to Caddy's admin API.

EDIT: this was fixed by adding my Docker container's IP address to the allowed list on the firewall with ufw