Added the other overload of TrySetCanceled on AvailabilityTests
Added the other overload of TrySetCanceled on AvailabilityTests

Again, I do not know why Visual Studio says that on .NET 4.6 both overloads exist here on TestRunner... but on Tests it says that the overload with CanellationToken on .NET 4.6 does not exist.
theraot/Theraot