try

announcement.gemspec

@@ -33,13 +33,13 @@ if old_gemfile_text != new_gemfile_text
   File.open(ENV['PWD']+'/Gemfile', 'w') do |file|
     file.write new_gemfile_text
   end
-  a = Thread.new do
-    Bundler.with_clean_env do
-      system("bundle update")
-      puts 'test123'
-    end
-  end
-  a.join()
+  #a = Thread.new do
+  #  Bundler.with_clean_env do
+  #    system("bundle update")
+  #    puts 'test123'
+  #  end
+  #end
+  #a.join()
   Thread.exit
 end
 # Describe your gem and declare its dependencies: