def call(env)
      @app.call(env).on_complete do |response_env|
        datetime = sunset_header(response_env.response_headers)
        report_deprecated_usage(env, datetime) unless datetime.nil?
      end
    end
def call(env)
      @app.call(env).on_complete do |response_env|
        datetime = sunset_header(response_env.response_headers)
        report_deprecated_usage(env, datetime) unless datetime.nil?
      end
    end
Initialize the middleware

 @param [Type] app describe app
 @param [Hash] options = {}
 @return void
 @param [Faraday::Env] no idea what this does
 @return [Faraday::Response] response from the middleware