Auto create PR when a new Velero GA version is released

[jenting]

Describe the problem/challenge you have
[A description of the current limitation/problem/challenge that you are experiencing.]

Sometimes, we'd forget to bump the Velero helm chart for a new Velero GA version is released.

Describe the solution you'd like

Have an automatic way (e.g., GitHub Action) to create a PR when a new Velero GA version is released.
The GitHub action could be implemented in vmware-tanzu/velero or vmware-tanzu/helm-chart repo, listening to the Velero GA version by webhook, then creating the helm chart PR to bump the Velero version.

Anything else you would like to add:
[Miscellaneous information that will assist in solving the issue.]

Original Slack discussion
https://kubernetes.slack.com/archives/C021GPR1L3S/p1648049297331879

Environment:

• helm version (use helm version):
• helm chart version and app version (use helm list -n <YOUR NAMESPACE>):
• Kubernetes version (use kubectl version):
• Kubernetes installer & version:
• Cloud provider or hardware configuration:
• OS (e.g. from /etc/os-release):

[jenting]

We use dependabot to auto-create the PR, closing this issue.