[BUGFIX] Adjust acceptance test for composer max stages

The test fails in recent runs due to a type error. It expects an integer,
but gets served a string and therefore fails.
Adjusting the expected value to be a string solves the test failure.

Resolves: #92496
Releases: master, 10.4
Change-Id: I6289502e7f44c3ec826138b32bdfa8e775565fb1
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/66063


Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Markus Klein <markus.klein@typo3.org>
Tested-by: Georg Ringer <georg.ringer@gmail.com>
Reviewed-by: Markus Klein <markus.klein@typo3.org>
Reviewed-by: Oliver Klee <typo3-coding@oliverklee.de>
Reviewed-by: Georg Ringer <georg.ringer@gmail.com>