www/py-pelican: update to 4.9.1

• switch build backend
• remove broken test part, since there is no broken test in the current version

Changelog: https://docs.getpelican.com/en/stable/changelog.html

PR: 275284
MFH: 2024Q1
(cherry picked from commit 7e62a21f319db9af00d5c5ea77e8ccd1e6440569)