Fix yq command in release template

The following discussion from !451 (merged) should be addressed:

• @maarten started a discussion: (+2 comments)

  find flux2/* -type f -exec yq eval .spec.chart {} \;
  Error: open flux2/apps/nextcloud/pvc.yaml: no such file or directory
  Error: open flux2/apps/nextcloud/release.yaml: no such file or directory
  Error: open flux2/apps/nextcloud/kustomization.yaml: no such file or directory
  Error: open flux2/apps/rocketchat/release.yaml: no such file or directory
  Error: open flux2/apps/rocketchat/kustomization.yaml: no such file or directory
  Error: open flux2/apps/velero/release.yaml: no such file or directory
  Error: open flux2/apps/velero/kustomization.yaml: no such file or directory
  Error: open flux2/apps/monitoring/pvc.yaml: no such file or directory
  Error: open flux2/apps/monitoring/loki-configmap.yaml: no such file or directory
  Error: open flux2/apps/monitoring/promtail-release.yaml: no such file or directory
  Error: open flux2/apps/monitoring/kube-prometheus-stack-release.yaml: no such file or directory
  Error: open flux2/apps/monitoring/eventrouter-release.yaml: no such file or directory
  Error: open flux2/apps/monitoring/loki-release.yaml: no such file or directory
  Error: open flux2/apps/monitoring/kustomization.yaml: no such file or directory
  Error: open flux2/apps/wordpress/pvc.yaml: no such file or directory
  Error: open flux2/apps/wordpress/release.yaml: no such file or directory
  ...