Prepare to publish (dart-lang/stream_transform#87)

pkgs/stream_transform/CHANGELOG.md

diff --git a/pkgs/stream_transform/CHANGELOG.md b/pkgs/stream_transform/CHANGELOG.md
index 52b1c51..d9b0049 100644
--- a/pkgs/stream_transform/CHANGELOG.md
+++ b/pkgs/stream_transform/CHANGELOG.md
@@ -1,4 +1,4 @@
-## 0.0.20-dev
+## 0.0.20
 
 -   Add extension methods for most transformers. These should be used in place
     of the current methods. All current implementations are deprecated and will

pkgs/stream_transform/pubspec.yaml

diff --git a/pkgs/stream_transform/pubspec.yaml b/pkgs/stream_transform/pubspec.yaml
index 803cc2e..8528f21 100644
--- a/pkgs/stream_transform/pubspec.yaml
+++ b/pkgs/stream_transform/pubspec.yaml
@@ -2,10 +2,10 @@
 description: A collection of utilities to transform and manipulate streams.
 author: Dart Team <misc@dartlang.org>
 homepage: https://www.github.com/dart-lang/stream_transform
-version: 0.0.20-dev
+version: 0.0.20
 
 environment:
-  sdk: ">=2.6.0-dev.5.0 <3.0.0"
+  sdk: ">=2.6.0 <3.0.0"
 
 dev_dependencies:
   pedantic: ^1.5.0