rabbit.gemspec in rabbit-2.1.9 vs rabbit.gemspec in rabbit-2.2.0

@@ -41,12 +41,13 @@
   spec.test_files = Dir.glob("test/**/*.rb")
   Dir.chdir("bin") do
     spec.executables = Dir.glob("*")
   end
 
-  spec.required_ruby_version = ">= 1.9.3"
+  spec.required_ruby_version = ">= 2.1.0"
 
   spec.add_runtime_dependency("gio2")
+  spec.add_runtime_dependency("gdk_pixbuf2", ">= 3.0.9")
   spec.add_runtime_dependency("gtk2")
   spec.add_runtime_dependency("rsvg2")
   spec.add_runtime_dependency("poppler")
   spec.add_runtime_dependency("hikidoc")
   spec.add_runtime_dependency("nokogiri")