Bug: helm-diff shows `- labels`, if resource contains only `app.kubernetes.io/managed-by` label

[jkroepke]

Hi!

before 3.15.12, I could observe the following diff on each resource:

  apiVersion: external-secrets.io/v1
  kind: ExternalSecret
  metadata:
    finalizers:
    - externalsecrets.external-secrets.io/externalsecret-cleanup
-   labels:
-     app.kubernetes.io/managed-by: Helm
    name: webhook-token
    namespace: flux-system
  spec:
    data:
    - remoteRef:

Now, with 3.15.12, the label is omit. But if its the only label on the resource, labels will be omit, too:

  apiVersion: external-secrets.io/v1
  kind: ExternalSecret
  metadata:
    finalizers:
    - externalsecrets.external-secrets.io/externalsecret-cleanup
-   labels:
    name: webhook-token
    namespace: flux-system
  spec:
    data:
    - remoteRef:

This leads into a confusing diff.