Retrohunt leverages indicator `valid_from` attribute 🔍

As soon as a new indicator is added to the SEKOIA.IO knowledge base, a systematic search is carried out to check whether this indicator has already been observed in the past. This feature is called **retrohunt**. Today, we have improved the retrohunt so that it takes into account the validity date of the indicator (`valid_from`) to establish the time window of the search.