`clean` command does not work with POST /backup/actions.

[joelbandi]

# curl -X POST -d '{"command":"clean"}' localhost:7171/backup/actions
{"status":"error","operation":"clean","error":"unknown command"}

# clickhouse-backup version
Version:     2.4.2
Git Commit:  8f6fe6b26fad2390dd9d7223b86296cba57b22e8
Build Date:  2023-10-12

clickhouse-server version: 23.8.3.48

Looks like were missing a case for clean in this switch statement in the api response handler https://github.com/Altinity/clickhouse-backup/blob/e111dc47f449ac92ca9291f0daf836c543b78009/pkg/server/server.go#L347

[Slach]

thanks for reporting