Use google-protobuf 3.4.0.2

cbcbe4b7 · Jacob Vosmaer · c1f12ff5 · cbcbe4b7
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -329,7 +329,7 @@ GEM
      multi_json (~> 1.10)
      retriable (~> 1.4)
      signet (~> 0.6)
-    google-protobuf (3.3.0)
+    google-protobuf (3.4.0.2)
    googleauth (0.5.1)
      faraday (~> 0.9)
      jwt (~> 1.4)