[TASK] Remove TODO to mark PageRenderer final

It was decided that PageRenderer won't become final.

Resolves: #102752
Releases: main
Change-Id: I19001ae5f89ca89930d6dc381ace12e92ca815d2
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/82310


Tested-by: Benni Mack <benni@typo3.org>
Tested-by: Chris Müller <typo3@krue.ml>
Tested-by: core-ci <typo3@b13.com>
Tested-by: Torben Hansen <derhansen@gmail.com>
Reviewed-by: Torben Hansen <derhansen@gmail.com>
Tested-by: Oliver Klee <typo3-coding@oliverklee.de>
Reviewed-by: Benni Mack <benni@typo3.org>
Reviewed-by: Oliver Klee <typo3-coding@oliverklee.de>
Reviewed-by: Chris Müller <typo3@krue.ml>