swagger-ui as middleware & upgrade to 3.12.2

rswag-ui/lib/tasks/rswag-ui_tasks.rake

@@ -0,0 +1,12 @@
+namespace :rswag do
+  namespace :ui do
+
+    desc 'TODO'
+    task :copy_assets, [ :dest ] do |t, args|
+      dest = args[:dest]
+      FileUtils.rm_r(dest, force: true)
+      FileUtils.mkdir_p(dest)
+      FileUtils.cp_r(Dir.glob("#{Rswag::Ui.config.assets_root}/{*.js,*.png,*.css}"), dest)
+    end
+  end
+end