External Libraries: Update the SimplePie library to version 1.8.0.
The most notable change in this update is that all code is now namespaced and uses PSR-4 classes, though there is a compatibility layer available for extenders using the older class names, so plugin or theme authors directly using SimplePie can decide for themselves when they want to change to using the namespaced names for SimplePie classes.
Note: This commit includes additional fixes for PHP 8.4 compatibility (PR 875, PR 888) from the one-dot-eight branch of SimplePie, which is expected to be released as SimplePie 1.8.1 soon.
References:
Follow-up to [47733], [49176], [52393], [52413].
Props jrf, peterwilsoncc, chaion07, cu121, markparnell, audrasjb, costdev, Presskopp, desrosj, faisal03, mukesh27, SergeyBiryukov.
See #55604.