Create python3 version of textproc/py-feedparser. This require approval from
portmgr to commit PR https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=217480
beaucse it's blocked by the pre commit hook about FLAVORS. This PR is a blocker
to add a new port misc/py-gitsome port in PR
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=217484.