Bump to 0.12.30 before publishing. (#736)

Bump to 0.12.29+1 before publishing.
diff --git a/pubspec.yaml b/pubspec.yaml
index a7dc7a6..a346418 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -1,5 +1,5 @@
 name: test
-version: 0.12.30-dev
+version: 0.12.29+1
 author: Dart Team <misc@dartlang.org>
 description: A library for writing dart unit tests.
 homepage: https://github.com/dart-lang/test