Merge pull request #39 from tbetbetbe/grpc_ruby_update_protobuf_ruby_version

Updates to use the latest version of protobuf-ruby
diff --git a/src/ruby/grpc.gemspec b/src/ruby/grpc.gemspec
index 3e1dcd5..53fdd29 100755
--- a/src/ruby/grpc.gemspec
+++ b/src/ruby/grpc.gemspec
@@ -19,7 +19,7 @@
 
   s.add_dependency 'xray'
   s.add_dependency 'logging', '~> 1.8'
-  s.add_dependency 'google-protobuf', '~> 3.0.0alpha'
+  s.add_dependency 'google-protobuf', '~> 3.0.0alpha.1.1'
   s.add_dependency 'minitest', '~> 5.4'  # not a dev dependency, used by the interop tests
 
   s.add_development_dependency "bundler", "~> 1.7"