[TEST] Apache Struts 7.2.1 test build is ready

This is a minor release of Struts 7.x which contains a few slightly
breaking changes (read the version notes). Please take the time and
test the bits - any help is appreciated. Please report any problems
you will spot.

Here are the changes from the previous version:
https://github.com/apache/struts/releases/tag/STRUTS_7_2_1

Staging Maven repo
https://repository.apache.org/content/groups/staging/

Standalone artifacts
https://dist.apache.org/repos/dist/dev/struts/7.2.1/

Release notes
https://cwiki.apache.org/confluence/display/WW/Version+Notes+7.2.1