Remove -dev.infinity in SDK upper constraint

Author: kevmoo

pubspec.yaml

@@ -5,7 +5,7 @@ author: Dart Team <[email protected]>
 homepage: https://github.com/dart-lang/web_socket_channel
 
 environment:
-  sdk: '>=1.13.0 <2.0.0-dev.infinity'
+  sdk: '>=1.13.0 <2.0.0'
 
 dependencies:
   async: '^1.3.0'