[BUGFIX] Fix PHP 8 warning in ContentObjectRenderer

Resolves: #98966
Resolves: #98425
Releases: main, 11.5
Change-Id: Idd8b3d7db8c7455cfbdd39a534a3995d33c651cd
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/77563


Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: core-ci <typo3@b13.com>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Andreas Fernandez <a.fernandez@scripting-base.de>
Reviewed-by: Andreas Fernandez <a.fernandez@scripting-base.de>