Bump version (#20)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index a315133..e42859a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,7 @@
+### 2.2.1
+
+* Add `operatingSystemVersion`
+
 ### 2.2.0
 
 * Declare compatibility with Dart 2 stable
diff --git a/pubspec.yaml b/pubspec.yaml
index 1209014..1e3c40a 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -1,5 +1,5 @@
 name: platform
-version: 2.2.0
+version: 2.2.1
 authors:
 - Todd Volkert <tvolkert@google.com>
 description: A pluggable, mockable platform abstraction for Dart.