Prepare release with topics (dart-lang/yaml#144)

pkgs/yaml/CHANGELOG.md

diff --git a/pkgs/yaml/CHANGELOG.md b/pkgs/yaml/CHANGELOG.md
index 2a4cc16..2a78ef9 100644
--- a/pkgs/yaml/CHANGELOG.md
+++ b/pkgs/yaml/CHANGELOG.md
@@ -1,6 +1,7 @@
-## 3.1.2-dev
+## 3.1.2
 
 * Require Dart 2.19
+* Added `topics` in `pubspec.yaml`.
 
 ## 3.1.1
 

pkgs/yaml/pubspec.yaml

diff --git a/pkgs/yaml/pubspec.yaml b/pkgs/yaml/pubspec.yaml
index 899ed0f..a3290e1 100644
--- a/pkgs/yaml/pubspec.yaml
+++ b/pkgs/yaml/pubspec.yaml
@@ -1,7 +1,10 @@
 name: yaml
-version: 3.1.2-dev
+version: 3.1.2
 description: A parser for YAML, a human-friendly data serialization standard
 repository: https://github.com/dart-lang/yaml
+topics:
+ - yaml
+ - config-format
 
 environment:
   sdk: '>=2.19.0 <3.0.0'