Backend v3 incorrect `createdAt` property on `PublishedData`

[fpotier]

Looks like the createdAt property is not present in the db for PublishedData and is automatically replaced by the current date.

for ((i=0; i<5; i++)); do 
    curl https://dacat.psi.ch/api/v3/publisheddata/10.16907%2F808de0df-a9d3-4698-8e9f-d6e091516650 -s | jq .createdAt
done

Outputs:

"2025-04-23T11:58:47.674Z"
"2025-04-23T11:58:47.969Z"
"2025-04-23T11:58:48.408Z"
"2025-04-23T11:58:48.725Z"
"2025-04-23T11:58:49.009Z"