Add source "Workflow" for Subscriber Property

[kummelkorn]

When I get subscriber properties from Expertsender, get error "Value 'Workflow' is not part of the enum Citilink\ExpertSenderApi\Enum\SubscriberPropertySource".
I checked sources for all properties and got some fields with source "Workflow", but it is not described in manual (https://manual.expertsender.ru/metody/podpischiki/poluchit-informatsiyu-o-podpischike). This fields was assigned in workflow scripts.