Use CronJob batch/v1 resource version if available

[ikeeip]

The batch/v2alpha1 CronJob type definitions and clients are deprecated and removed in Kubernetes v1.21. This patch fix deprecation warnings related to version change.

Kubernetes v1.20.7 output:

$ kubectl version | grep Server
Server Version: version.Info{Major:"1", Minor:"20", GitVersion:"v1.20.7", GitCommit:"132a687512d7fb058d0f5890f07d4121b3f0a2e2", GitTreeState:"clean", BuildDate:"2021-05-27T23:27:49Z", GoVersion:"go1.15.12", Compiler:"gc", Platform:"linux/amd64"}

$ helm install foo deploy/helm/kubernetes --dry-run | grep -B1 CronJob
apiVersion: batch/v1beta1
kind: CronJob

Kubernetes v1.21.1 output:

$ kubectl version | grep Server
Server Version: version.Info{Major:"1", Minor:"21", GitVersion:"v1.21.1", GitCommit:"5e58841cce77d4bc13713ad2b91fa0d961e69192", GitTreeState:"clean", BuildDate:"2021-05-21T23:01:33Z", GoVersion:"go1.16.4", Compiler:"gc", Platform:"linux/amd64"}

$ helm install foo deploy/helm/kubernetes --dry-run | grep -B1 CronJob
apiVersion: batch/v1
kind: CronJob

[kvaps]

Hi thank you for your contribution and sorry for late reply,

In order to keep this chart as compatible as possible with the other management and templating tools, eg argocd and jsonnet. I'd like to avoid using lookup and capabilities feature.
This would allow you to render simple yaml without accessing end cluster, and just apply it when it will be needed.

Thus, let's just update the apiVersion and bump required Kubernetes version in README.md file

[ikeeip]

Thus, let's just update the apiVersion and bump required Kubernetes version in README.md file

Done!

[kvaps]

Looks good, thank you!