net/x2goclient-cli: Add missing setsid dependency

% x2goclient-cli --user <user> --server <server>

Password:
sh: setsid: not found
sh: setsid: not found
sh: setsid: not found
sh: setsid: not found
sh: setsid: not found

PR: 253449
Reported by: parv.0zero9+freebsd@gmail.com
Approved by: maintainer timeout

(cherry picked from commit 5660dfa864eb4c72e71531dec6823d66a365c41e)