Update Kubernetes version to 1.28.8

cesnet-central/playbooks/k8s.yaml

@@ -119,7 +119,7 @@
       vars:
         # do not downgrade docker
         kube_docker_version: latest
-        kube_version: 1.28.2
+        kube_version: 1.28.8
         kube_network: 'none'  # custom network installation
         kube_install_helm: true
         kube_install_helm_version: 'v3.13.0'
@@ -178,7 +178,7 @@
         # must be IPv4 address or hostname
         kube_server: "{{ hostvars[groups['master'][0]].kube_server | default(groups['master'][0]) }}"
         kube_type_of_node: wn
-        kube_version: 1.28.2
+        kube_version: 1.28.8
         kubelet_extra_args: '--volume-stats-agg-period 0'
 
 - name: K8s customization