[ DDS ] Prepare for 5.0.4 release

Change-Id: I04f4b78464e8cdfd6f61cbe57c6d5f0597a1fad0
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/435880
Reviewed-by: Kenzie Davisson <kenzieschmoll@google.com>
Auto-Submit: Ben Konyi <bkonyi@google.com>
Commit-Queue: Kenzie Davisson <kenzieschmoll@google.com>

pkg/dds/pubspec.yaml

@@ -1,5 +1,5 @@
 name: dds
-version: 5.0.4-wip
+version: 5.0.4
 description: >-
   A library used to spawn the Dart Developer Service, used to communicate with
   a Dart VM Service instance.