v0.51.3155

• New: Removed the new() requirement for read models
• New: If ISagaLocator.LocateSagaAsync cannot identify the saga for a given
  event, it may now return Task.FromResult(null) in order to short-circuit
  the dispatching process. This might be useful in cases where some instances
  of an event belong to a saga process while others don't
• Fixed: StringExtensions.ToSha256() can now be safely used from
  concurrent threads.