Fix ociReference formatting in collection-index.yml

Author: abdurriq

_data/collection-index.yml

@@ -1520,4 +1520,4 @@
   maintainer: aqua
   contact: https://github.com/aqua/devcontainer-gcloud/issues
   repository: https://github.com/aqua/devcontainer-gcloud
-  ociReference: ghcr.io/aqua/devcontainer-gcloud
+  ociReference: ghcr.io/aqua/devcontainer-gcloud