Merge pull request #36 from dart-lang/devoncarew-patch-1

Update pubspec.yaml
diff --git a/pubspec.yaml b/pubspec.yaml
index f162ae8..c67030c 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -4,7 +4,7 @@
 repository: https://github.com/dart-lang/clock
 
 environment:
-  sdk: ">=2.12.0-0 <3.0.0"
+  sdk: ">=2.12.0 <3.0.0"
 
 dev_dependencies:
   lints: ^1.0.0