fixed middleware's response

lib/telegram/bot/middleware.rb

@@ -15,7 +15,7 @@ module Telegram
       def call(env)
         update = env['action_dispatch.request.request_parameters']
         controller.dispatch(bot, update)
-        [200, {}, '']
+        [200, {}, ['']]
       end
 
       def inspect

lib/telegram/bot/version.rb

@@ -1,6 +1,6 @@
 module Telegram
   module Bot
-    VERSION = '0.4.1'.freeze
+    VERSION = '0.4.2'.freeze
 
     def self.gem_version
       Gem::Version.new VERSION

spec/telegram/bot/middleware_spec.rb

@@ -13,6 +13,6 @@ RSpec.describe Telegram::Bot::Middleware do
       subject
     end
 
-    it { should eq [200, {}, ''] }
+    it { should eq [200, {}, ['']] }
   end
 end