deprecaton of label_beta_kubernetes_io_instance_type

[marianobilli]

Due to deprecation of label_beta_kubernetes_io_instance_type
https://kubernetes.io/docs/reference/labels-annotations-taints/#beta-kubernetes-io-instance-type-deprecated

if possible update to label_node_kubernetes_io_instance_type in the labels of the instance cost metrics.

Thanks!

[kaskol10]

Thanks for your request @marianobilli . I'll create a PR this week with your request