Release v7.28.1

Changed

• The reactor rules and the reactor, slice-specification and C# specification skills teach the Chronicle 19.46.0 ReactorScenario behavior: a reactor handler's read-model parameter must be seeded, or declared absent with Given.ForEventSourceId(id).NoReadModel<T>(), otherwise the scenario throws ReadModelNotSeededForReactorScenario naming the type and key; a handler that throws synchronously surfaces its own exception; and EventContext.Occurred defaults to UTC. They no longer say the read model arrives as null (#599)