bump Dart SDK constraint (flutter#99)

* bump Dart SDK constraint

* Update pubspec.yaml

* => 2.0.1

Author: pq

packages/file/pubspec.yaml

@@ -1,5 +1,5 @@
 name: file
-version: 5.0.1
+version: 5.0.2
 authors:
 - Matan Lurey <matanl@google.com>
 - Yegor Jbanov <yjbanov@google.com>
@@ -17,4 +17,4 @@ dev_dependencies:
   file_testing: '>=2.0.0 <3.0.0'
 
 environment:
-  sdk: '>=2.0.0-dev.54.0 <2.0.0'
+  sdk: '>=2.0.0-dev.54.0 <3.0.0'

packages/file_testing/pubspec.yaml

@@ -1,5 +1,5 @@
 name: file_testing
-version: 2.0.0
+version: 2.0.1
 authors:
 - Todd Volkert <tvolkert@google.com>
 description: Testing utilities for package:file
@@ -10,4 +10,4 @@ dependencies:
   test: ^0.12.33
 
 environment:
-  sdk: '>=2.0.0-dev.28.0 <2.0.0'
+  sdk: '>=2.0.0-dev.28.0 <3.0.0'