[en] Fix unclosed code block

content/en/docs/tasks/administer-cluster/kubeadm/kubeadm-upgrade.md

@@ -266,6 +266,7 @@ without compromising the minimum required capacity for running your workloads.
   apt-mark unhold kubelet kubectl && \
   apt-get update && apt-get install -y kubelet={{< skew currentVersion >}}.x-00 kubectl={{< skew currentVersion >}}.x-00 && \
   apt-mark hold kubelet kubectl
+  ```
   {{% /tab %}}
   {{% tab name="CentOS, RHEL or Fedora" %}}
   ```shell