Fix a crash when view model's continueButtonTapped is called not on the main thread because it's not a main actor.

Author: jaclync

WooCommerce/Classes/Authentication/Store Creation/Profiler/Country/StoreCreationCountryQuestionViewModel.swift

@@ -2,6 +2,7 @@ import Combine
 import Foundation
 
 /// View model for `StoreCreationCountryQuestionView`, an optional profiler question about store country in the store creation flow.
+@MainActor
 final class StoreCreationCountryQuestionViewModel: StoreCreationProfilerQuestionViewModel, ObservableObject {
     typealias CountryCode = SiteAddress.CountryCode