Add model_version on WorkerActivity APIs

Requires !2087 (merged), closes #1560 (closed)

changed milestone to %Arkindex 1.5.1

requested review from @vrigal

assigned to @erouchet

added 4 commits

• 1256ae11...07c2ba17 - 3 commits from branch master
• 4d578000 - Expose model versions on WorkerActivity APIs

Compare with previous version

enabled an automatic merge when the pipeline for 4d578000 succeeds

merged