Update Intl version to 0.15.3

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=189762840
diff --git a/pubspec.yaml b/pubspec.yaml
index 9c14eda..b94ed7e 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -1,5 +1,5 @@
 name: intl
-version: 0.15.3-dev
+version: 0.15.3
 author: Dart Team <misc@dartlang.org>
 description: Contains code to deal with internationalized/localized messages, date and number formatting and parsing, bi-directional text, and other internationalization issues.
 homepage: https://github.com/dart-lang/intl