Prepare to publish for stable null safety (#20)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 075f4b4..be42e9d 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,7 @@
+## v0.3.0
+
+* Stable version for null safety.
+
 ## v0.3.0-nullsafety.0
 
 * **BREAKING** `SyncHttpClient` functions now require the `url` parameter to be
diff --git a/pubspec.yaml b/pubspec.yaml
index 1ee819c..a8a5ef8 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -1,5 +1,5 @@
 name: sync_http
-version: 0.3.0-nullsafety.0
+version: 0.3.0
 description: Synchronous HTTP client for Dart.
 homepage: https://github.com/dart-lang/sync_http