skaffold render doesn't support helm chart version templating

## Expected behavior

The version of helm charts should be able to be templated when we use `skaffold render`, as it's supported in `skaffold deploy`.

## Actual behavior

skaffold render will return error if we want to expand the version of helm chart from environment variables.

Take this simple config as an example

```yaml
apiVersion: skaffold/v4beta12
kind: Config
metadata:
name: istio-release
deploy:
helm:
releases:
- name: istiod
namespace: istio-release
createNamespace: true
remoteChart: oci://gcr.io/istio-release/charts/istiod
version: "{{.ISTIO_VERSION}}"
wait: true
```

## Steps to reproduce the behavior

Run skaffold render with the above config.

```bash
export ISTIO_VERSION=1.28.0
skaffold render
```

it will return the following error:

> Failed to render release: Error: improper constraint: {{.ISTIO_VERSION}}
> (releaseName="istiod", args=[template istiod oci://gcr.io/istio-release/charts/istiod --version {{.ISTIO_VERSION}} --namespace istio-release])