[package:vm_service] Prepare to publish version 15.0.1

Change-Id: I3e9ccc809bc031c1015eaacd266e41ac8475b1fc
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/430140
Commit-Queue: Derek Xu <derekx@google.com>
Reviewed-by: Ben Konyi <bkonyi@google.com>

pkg/vm_service/CHANGELOG.md

@@ -1,4 +1,4 @@
-## 15.0.1-wip
+## 15.0.1
 - Update to version `4.19` of the spec.
 - Add `Timer` stream.
 - Add `TimerSignificantlyOverdue` event kind.

pkg/vm_service/pubspec.yaml

@@ -1,5 +1,5 @@
 name: vm_service
-version: 15.0.1-wip
+version: 15.0.1
 description: >-
   A library to communicate with a service implementing the Dart VM
   service protocol.