Prepare to publish (dart-lang/web_socket_channel#174)

pkgs/web_socket_channel/CHANGELOG.md

diff --git a/pkgs/web_socket_channel/CHANGELOG.md b/pkgs/web_socket_channel/CHANGELOG.md
index da9bb62..a2c9f95 100644
--- a/pkgs/web_socket_channel/CHANGELOG.md
+++ b/pkgs/web_socket_channel/CHANGELOG.md
@@ -1,4 +1,4 @@
-## 2.1.0-dev
+## 2.1.0
 
 - Add `IOWebSocketChannel.innerWebSocket` getter to access features not exposed
   through the shared `WebSocketChannel` interface.

pkgs/web_socket_channel/pubspec.yaml

diff --git a/pkgs/web_socket_channel/pubspec.yaml b/pkgs/web_socket_channel/pubspec.yaml
index 5e40dcc..6d61fb3 100644
--- a/pkgs/web_socket_channel/pubspec.yaml
+++ b/pkgs/web_socket_channel/pubspec.yaml
@@ -1,5 +1,5 @@
 name: web_socket_channel
-version: 2.1.0-dev
+version: 2.1.0
 
 description: >-
   StreamChannel wrappers for WebSockets. Provides a cross-platform