TBR mojo/v23proxy: Fix this package too

mojo_sdk is 0.2.19

Change-Id: Ia05aaec1d9863695333e0f9d07b43e8e7dc3d092
diff --git a/dart-tests/end_to_end_test/pubspec.yaml b/dart-tests/end_to_end_test/pubspec.yaml
index ce37580..44dc6bb 100644
--- a/dart-tests/end_to_end_test/pubspec.yaml
+++ b/dart-tests/end_to_end_test/pubspec.yaml
@@ -4,7 +4,7 @@
 name: v23proxy_end_to_end_test
 version: 0.0.1
 dependencies:
-  mojo_sdk: 0.2.16
+  mojo_sdk: 0.2.19
   v23proxy: '>=0.0.1'
 environment:
   sdk: '>=1.12.0 <2.0.0'