更新 remmina 为新版 VirtualBox 自动重连接正常

更新 remmina  方法：

#echo 'deb http://ftp.debian.org/debian stretch-backports main' | sudo tee --append /etc/apt/sources.list.d/stretch-backports.list >> /dev/null

echo 'deb https://mirrors.tuna.tsinghua.edu.cn/debian stretch-backports main' | sudo tee --append /etc/apt/sources.list.d/stretch-backports.list >> /dev/null

echo 'deb http://mirrors.aliyun.com/debian/ stretch-backports main' | sudo tee --append /etc/apt/sources.list.d/stretch-backports.list >> /dev/null

sudo apt update

sudo apt install -t stretch-backports remmina remmina-plugin-rdp remmina-plugin-secret libfreerdp-plugins-standard