Cannot define patches for properties that have been changed in newer versions

From a user report on slack, consider the patch:
```
patches:
- op: add
path: /deploy/helm/releases/0
value:
name: docs
namespace: documentation
chartPath: ./documentation/helm
remote: false
values:
image: docs
```
This is consistent for skaffold API version `skaffold/v1` but in newer versions `value` property of the helm deployer has been renamed to `artifactOverride`. This patch fails to get applied as it's not upgraded to the latest version properly unlike the regular `Pipeline` objects [do](https://github.com/GoogleContainerTools/skaffold/blob/master/pkg/skaffold/schema/util/upgrade_pipelines.go#L31).