cmd: fix config flag

[scriptnull]

Before

$ go run main.go server --config ./config/config.yaml 
Error: unknown flag: --config
Usage:
  gokakashi server [flags]

Flags:
  -h, --help   help for server

unknown flag: --config
exit status 1

After

$ go run main.go server --config ./config/config.yaml 
2024/10/27 07:42:14 === Starting goKakashi Tool ===
2024/10/27 07:42:14 Loading configuration from YAML file: ./config/config.yaml
2024/10/27 07:42:14 Error: configuration validation failed: websites cannot be empty
exit status 1