Merge pull request dart-lang/yaml#29 from dart-lang/devoncarew-patch-1

Update pubspec.yaml

pkgs/yaml/pubspec.yaml

diff --git a/pkgs/yaml/pubspec.yaml b/pkgs/yaml/pubspec.yaml
index d4445d9..2b65030 100644
--- a/pkgs/yaml/pubspec.yaml
+++ b/pkgs/yaml/pubspec.yaml
@@ -12,4 +12,4 @@
   path: ">=1.2.0 <2.0.0"
   test: ">=0.12.0 <0.13.0"
 environment:
-  sdk: '>=1.12.0 <2.0.0'
+  sdk: '>=1.12.0 <2.0.0-dev.infinity'