Description of problem:
`last_generated_content_on` doesn't update on automating the generation of widget content Via RESTAPI

Version-Release number of selected component (if applicable):
5.10.12

How reproducible:
Always

Steps to Reproduce:
0. GET /api/widgets/:id and note the `last_generated_content_on`.
1. POST /api/widgets/:id
{
    "action": "generate_content"
}
2. Wait until the task completes
3. GET /api/widgets/:id and compare the value of `last_generated_content_on` with the value noted in step 0.

Actual results:
0.
1.
2.
3. Value does not change.
Expected results:
0.
1.
2.
3. Value must be updated

Additional info:
Reference BZ: https://bugzilla.redhat.com/show_bug.cgi?id=1753682