[BUGFIX] Fix HTTP test for manuals on docs.typo3.org

Resolves: #58347
Releases: current
Change-Id: I9ff864fcbec3573d9de79cebdee340bbfa15e873
Reviewed-on: https://review.typo3.org/29732
Reviewed-by: Thomas Löffler
Tested-by: Thomas Löffler