Bump Data API client to 2.3.1 & fix column name for LatestVideo.userId

[sl-at-ibm]

This PR upgrades the required Data API client to v2.3.1, which includes a fix for the bug of missing support for some CQL types in primary keys.
This means that finally the insertion of a new video, i.e.

curl -k -X \
    POST "https://localhost:7264/api/v1/videos" \
   -H "Content-Type: application/json" -H "Authorization: Bearer $TOKEN" \
   -d '{"youtubeUrl":"https://www.youtube.com/watch?v=AAABBBCCC", "title":"Bla blabla"}'

runs without problems. (which also required adding an annotation for a column name along the way).