Ensure Digest field is not empty when calling VersionCheck endpoint

[kaidaguerre]

it is possible under certain circumstances when moving between version 14 and 13 that the
versions.json file may get currupted, clearing the image_digest field (amongst others)

if the Digest field of the Payload is empty, the API call will fail

if is missing, populate with dummy field - this will force and update and in doing so fix the versions.json