feat(rack-cors): update rack cors to ~> 1.1

[rjherrera]

This PR updates rack-cors in order to remove vulnerability warnings from freshly bundled potassium projects. After this PR we should address #202.

closes #265

[ldlsegovia]

Te parece que tengamos mejor algo como:

    config.middleware.insert_before 0, Rack::Cors do
      allow do
        origins '*'
        resource '/public/*', headers: :any, methods: :get

        resource '/api/*',
          headers: :any,
          methods: [:get, :post]
      end
    end

[rjherrera]

I suggested something very similar but I'll address that in other PR! Thank you