[TASK] Raise typo3/testing-framework to 6.4.7

Contains a change for an upcoming workspace related
core patch.

composer require --dev typo3/testing-framework ^6.4.7

Change-Id: I11980b635e3a2b00de481a8d73b69368554c08d3
Releases: master, 10.4
Resolves: #92818
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/66604


Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Oliver Bartsch <bo@cedev.de>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Oliver Bartsch <bo@cedev.de>
Reviewed-by: Oliver Klee <typo3-coding@oliverklee.de>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>