Compatibility with feed-io 3 and 4
rss-atom-bundle now comes with feed-io 4 if PHP's version is 7.1 or higher. It is still possible to use feed-io 3 by requiring it in composer.json like described here : https://github.com/alexdebril/rss-atom-bundle/blob/master/README.md#going-back-to-feed-io-30