[infra] Upgrade homebrew dependencies to work on Dart 2

Change-Id: I1f6cb435d4b57aef3bf5b60e4a8254dfe5ecc77d
Reviewed-on: https://dart-review.googlesource.com/67121
Reviewed-by: William Hesse <whesse@google.com>
diff --git a/tools/apps/update_homebrew/pubspec.yaml b/tools/apps/update_homebrew/pubspec.yaml
index b90401e..0645811 100644
--- a/tools/apps/update_homebrew/pubspec.yaml
+++ b/tools/apps/update_homebrew/pubspec.yaml
@@ -3,7 +3,7 @@
 dependencies:
   _discoveryapis_commons: ^0.1.3+1
   args: ^0.13.0
-  googleapis: ^0.35.0
+  googleapis: ^0.51.0
   http: ^0.11.1+1
   path: ^1.4.1
   stack_trace: ^1.3.2