fix: converting workflow results datetime objects (#1255)

[ArtArtem]

Describe the bug
When the result of a workflow execution might include datetime object, we're unable to save it in to the database because of a serialization problem.

Solution:
So now, according to mock testing data:
e.g.
mock_action1 = Mock(name="action1")
mock_action1.name = "action1"
mock_action 1.provider.results = {"result": "value1"}

results dict's fields will be iterated and datetime objects will be converted to be properly saved in DB

Needs to be double checked with relevant workflowexecution data

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Name	Status	Preview	Comments	Updated (UTC)
keep	⬜️ Ignored (Inspect)	Visit Preview		Jul 17, 2024 7:52am

[talboren]

Hey @ArtArtem
Thank you for this contribution! Unfortunately, this doesn't seem to be the right way to solve this issue. Please see: #1236 for more details.