Tweak to only pass along EventMessage payloads to developers as it's …

…expected that the initial response will be null if EventMessage is populated

Signed-off-by: Whit Waldo <whit.waldo@innovian.net>

src/Dapr.Messaging/PublishSubscribe/PublishSubscribeReceiver.cs

@@ -275,7 +275,8 @@ await stream.RequestStream.WriteAsync(
         await foreach (var response in stream.ResponseStream.ReadAllAsync(cancellationToken))
         {
             //https://github.com/dapr/dotnet-sdk/issues/1412 reports that this is sometimes null
-            if (response?.EventMessage is null || response.InitialResponse is null)
+            //Skip the initial response - we only want to pass along TopicMessage payloads to developers
+            if (response?.EventMessage is null)
             {
                 return;
             }