Support the latest build_runner (#101)

diff --git a/pubspec.yaml b/pubspec.yaml
index c1441de..9734515 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -1,5 +1,5 @@
 name: collection
-version: 1.14.11
+version: 1.14.12-dev
 
 description: Collections and utilities functions and classes related to collections.
 author: Dart Team <misc@dartlang.org>
@@ -10,7 +10,7 @@
   sdk: '>=2.0.0-dev.55.0 <3.0.0'
 
 dev_dependencies:
-  build_runner: ^0.9.0
+  build_runner: ^1.0.0
   build_test: ^0.10.0
   build_web_compilers: ^0.4.0
   test: ^1.0.0