Publish Helm OCI charts without v prefix

[maboehm]

When looking for versions, helm does not consider semver tags starting with v, so helm install without a --version flag returns an error

helm upgrade --install designate-certmanager --namespace=cert-manager oci://ghcr.io/stackitcloud/charts/designate-certmanager-webhook
Release "designate-certmanager" does not exist. Installing it now.
Error: Unable to locate any tags in provided repository: oci://ghcr.io/stackitcloud/charts/designate-certmanager-webhook