[BUGFIX] Raise minimum version of typo3/testing-framework to 6.4.1

The changes in #91990 required at least version 6.4.1, but the version was
not pinned in composer.json to reflect that (only composer.lock was
updated). Therefore bamboo nightly composer min stage failed.

Used command:
	composer require --dev typo3/testing-framework:^6.4.1

Resolves: #92083
Related: #91990
Releases: master
Change-Id: I1397cc4d922e90c7864e2f7682b7d1ff1c59133c
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/65444


Tested-by: Benjamin Franzke <bfr@qbus.de>
Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Andreas Fernandez <a.fernandez@scripting-base.de>
Reviewed-by: Benjamin Franzke <bfr@qbus.de>
Reviewed-by: Richard Haeser <richard@richardhaeser.com>
Reviewed-by: Andreas Fernandez <a.fernandez@scripting-base.de>