graphics/qgis-ltr: Update to 3.28.8

Has to use embedded LazPerf again, since isn't able to recognize external.

Changelog: https://github.com/qgis/QGIS/compare/final-3_28_7%5E...final-3_28_8

Reported by: portscout, Repology
MFH: 2023Q3

(cherry picked from commit 81aafe016809ea615ab9b15cb48070743b469381)