Update example to latest publish packages (#130)

Author: kevmoo

example/README.md

@@ -8,11 +8,11 @@ dependencies to your `pubspec.yaml`.
 
 ```yaml
 dependencies:
-  json_annotation: ^0.2.2
+  json_annotation: ^0.2.3
 
 dev_dependencies:
-  build_runner: ^0.7.6
-  json_serializable: ^0.4.0
+  build_runner: ^0.8.0
+  json_serializable: ^0.5.0
 ```
 
 Annotate your code with classes defined in

example/pubspec.yaml

@@ -2,14 +2,14 @@ name: example
 author: Dart Team <misc@dartlang.org>
 
 environment:
-  sdk: '>=2.0.0-dev.9 <2.0.0'
+  sdk: '>=2.0.0-dev.32 <2.0.0'
 
 dependencies:
-  json_annotation: ^0.2.2
+  json_annotation: ^0.2.3
 
 dev_dependencies:
-  build_runner: ^0.7.6
-  json_serializable: ^0.4.0
+  build_runner: ^0.8.0
+  json_serializable: ^0.5.0
 
   # Used by tests. Not required to use `json_serializable`.
   path: ^1.5.1

example/test/readme_test.dart

@@ -20,9 +20,9 @@ void _expect(String fileName) {
 
 final _pubspecContent = r'''
 dependencies:
-  json_annotation: ^0.2.2
+  json_annotation: ^0.2.3
 
 dev_dependencies:
-  build_runner: ^0.7.6
-  json_serializable: ^0.4.0
+  build_runner: ^0.8.0
+  json_serializable: ^0.5.0
 ''';