Replace Apache abdera dependency

This library is used by document-generator to parse jira activity feeds. This activity feed info is an XML file which follows the https://activitystrea.ms/ format.

Apache Abdera last update was done in 2012 and is retired as per the Apache doc: https://abdera.apache.org/

Plus it pulls a transitive dependency (wstx-asl:3.2.6) which has been reported to have vulnerabilities.