[TASK] Raise testing framework to version 5.0.16

The next version has PHP 7.4 support and was
cleaned up a lot.

Used composer command:
    composer req typo3/testing-framework:~5.0.16 \
        --update-with-all-dependencies --dev

Resolves: #89725
Releases: master
Change-Id: Iba181feb693c9ee61b8792cd0d0197c1e3b1f59a
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/62359


Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Benni Mack <benni@typo3.org>
Reviewed-by: Benni Mack <benni@typo3.org>