题目：
Given an existing Kubernetes cluster running version 1.18.8upgrade all of the Kubernetes control plane and nodeComponents on the master node only to version 1.19.0 .
You are also expected to upgrade kubelet and kubectl on the master node.
Be sure to drain the master node before upgrading it and uncordon it after the upgrade.
Do not upgrade the worker nodes, etcd, the containermanager, the CNl plugin, the DNs sektice or any otheraddons.
文档：
https://v1-23.docs.kubernetes.io/zh/docs/tasks/administer-cluster/kubeadm/kubeadm-upgrade/
步骤：
kubectl cordon k8s-master
kubectl drain k8s-master --ignore-daemonsets