[cozystack-api] Fix resourceVersion error (#1170)

Signed-off-by: Andrei Kvapil <kvapss@gmail.com>

<!-- Thank you for making a contribution! Here are some tips for you:
- Start the PR title with the [label] of Cozystack component:
- For system components: [platform], [system], [linstor], [cilium],
[kube-ovn], [dashboard], [cluster-api], etc.
- For managed apps: [apps], [tenant], [kubernetes], [postgres],
[virtual-machine] etc.
- For development and maintenance: [tests], [ci], [docs], [maintenance].
- If it's a work in progress, consider creating this PR as a draft.
- Don't hesistate to ask for opinion and review in the community chats,
even if it's still a draft.
- Add the label `backport` if it's a bugfix that needs to be backported
to a previous version.
-->

## What this PR does

This PR fixes error:

```
failed to update HelmRelease: helmreleases.helm.toolkit.fluxcd.io "xxx" is invalid: metadata.resourceVersion: Invalid value: 0x0: must be specified for an update
```

### Release note

<!--  Write a release note:
- Explain what has changed internally and for users.
- Start with the same [label] as in the PR title
- Follow the guidelines at
https://github.com/kubernetes/community/blob/master/contributors/guide/release-notes.md.
-->

```release-note
[cozystack-api] Fix resourceVersion error
```

pkg/registry/apps/application/rest.go

@@ -425,6 +425,15 @@ func (r *REST) Update(ctx context.Context, name string, objInfo rest.UpdatedObje
 		return nil, false, fmt.Errorf("conversion error: %v", err)
 	}
 
+	// Ensure ResourceVersion
+	if helmRelease.ResourceVersion == "" {
+		cur, err := r.dynamicClient.Resource(helmReleaseGVR).Namespace(helmRelease.Namespace).Get(ctx, helmRelease.Name, metav1.GetOptions{})
+		if err != nil {
+			return nil, false, fmt.Errorf("failed to fetch current HelmRelease: %w", err)
+		}
+		helmRelease.SetResourceVersion(cur.GetResourceVersion())
+	}
+
 	// Merge system labels (from config) directly
 	helmRelease.Labels = mergeMaps(r.releaseConfig.Labels, helmRelease.Labels)
 	// Merge user labels with prefix