Updated gemspec to require Ruby 2.3 or higher
diff --git a/ruby/google-protobuf.gemspec b/ruby/google-protobuf.gemspec
index 2b095f4..0f7cc0a 100644
--- a/ruby/google-protobuf.gemspec
+++ b/ruby/google-protobuf.gemspec
@@ -20,6 +20,7 @@
s.test_files = ["tests/basic.rb",
"tests/stress.rb",
"tests/generated_code_test.rb"]
+ s.required_ruby_version = '>= 2.3'
s.add_development_dependency "rake-compiler", "~> 0.9.5"
s.add_development_dependency "test-unit", '~> 3.0', '>= 3.0.9'
s.add_development_dependency "rubygems-tasks", "~> 0.2.4"
