Prepare to publish (#233)

Drop `-dev` version suffix to publish.
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 5ebe8ec..6161476 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,4 +1,4 @@
-## 1.16.0-dev
+## 1.16.0
 
 * Add an `Iterable.slices` extension method.
 * Add `BoolList` class for space-efficient lists of boolean values.
diff --git a/pubspec.yaml b/pubspec.yaml
index ea2a2c0..ae623b8 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -1,5 +1,5 @@
 name: collection
-version: 1.16.0-dev
+version: 1.16.0
 
 description: Collections and utilities functions and classes related to collections.
 repository: https://github.com/dart-lang/collection