Cannot install the plugin with ArgoCD

I try to install this plugin with ArgoCD like this:
```
---
apiVersion: argoproj.io/v1alpha1
kind: Application
metadata:
name: cloudnativepg-operator
namespace: argocd
annotations:
argocd.argoproj.io/sync-wave: '0'
labels:
type: postgres
spec:
project: myproject
sources:
- chart: cloudnative-pg
repoURL: https://cloudnative-pg.github.io/charts
targetRevision: 0.28.2
helm:
releaseName: cloudnative-pg
# Install the barman plugin
- repoURL: https://github.com/cloudnative-pg/plugin-barman-cloud
targetRevision: v0.13.0
path: .
destination:
server: https://kubernetes.default.svc
namespace: cnpg-system
syncPolicy:
automated:
prune: true
selfHeal: true
syncOptions: [CreateNamespace=true, ServerSideApply=true]
```

ArgoCD complains with:
```
ComparisonError: Failed to load target state: failed to unmarshal manifests for source 2 of 2: Object 'Kind' is missing in '{".":"0.13.0","metadata":{"annotations":{"argocd.argoproj.io/tracking-id":"cloudnativepg-operator:/:cnpg-system/"}}}'
```

Reproduce the failure using the shown ArgoCD Application and the repository at targetRevision v0.13.0. Inspect what ArgoCD finds in the repository root for source 2 and determine why it produces an object without a Kind. Done means ArgoCD can load valid manifests for the plugin source without the ComparisonError.

Scritto dal modello di indicizzazione a partire dal testo della issue.