Prepare to publish (#54)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 9e56723..611aa71 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,4 +1,4 @@
-## 2.2.1-dev
+## 2.2.1
 
 * Fix `Peer` requests not terminating when the underlying channel is closed.
 
diff --git a/pubspec.yaml b/pubspec.yaml
index d030b6b..08c435a 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -1,5 +1,5 @@
 name: json_rpc_2
-version: 2.2.1-dev
+version: 2.2.1
 description: >-
   Utilities to write a client or server using the JSON-RPC 2.0 spec.
 homepage: https://github.com/dart-lang/json_rpc_2