Add Setapp Support

Setapp is a large collection of powerful Mac apps offered on a subscription basis. This means that users with an active Setapp subscription can also use Budget Flow without having to make a separate purchase or take out a subscription.

However, some questions need to be clarified before implementation (such as whether the app can be deployed automatically for both the App Store and Setapp as before).

Link to Setapp: https://setapp.com