Actually declare the version as 2.0.1.

R=rnystrom@google.com

Review URL: https://codereview.chromium.org//2034303002 .
diff --git a/pubspec.yaml b/pubspec.yaml
index 748452f..dee5503 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -1,5 +1,5 @@
 name: crypto
-version: 2.0.0
+version: 2.0.1
 author: Dart Team <misc@dartlang.org>
 description: Library of cryptographic functions.
 homepage: https://www.github.com/dart-lang/crypto