fix: 删除 screen.go 中未使用的 rfb 导入

删除 vnc 字段后，rfb 包不再被使用

Author: ZacharyZcR

mylib/grdp/login/screen.go

@@ -9,7 +9,6 @@ import (
 	"github.com/shadow1ng/fscan/mylib/grdp/glog"
 	"github.com/shadow1ng/fscan/mylib/grdp/protocol/nla"
 	"github.com/shadow1ng/fscan/mylib/grdp/protocol/pdu"
-	"github.com/shadow1ng/fscan/mylib/grdp/protocol/rfb"
 	"github.com/shadow1ng/fscan/mylib/grdp/protocol/sec"
 	"github.com/shadow1ng/fscan/mylib/grdp/protocol/t125"
 	"github.com/shadow1ng/fscan/mylib/grdp/protocol/tpkt"