[DOCS] Fix typo in workspaces event PHPDoc

This is relevant for the generated documentation.

Resolves: #100953
Releases: main, 12.4, 11.5
Change-Id: Iaa68d1cb21d399f326341cce2b12514a5402e45e
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/79131


Tested-by: core-ci <typo3@b13.com>
Reviewed-by: Benni Mack <benni@typo3.org>
Tested-by: Benni Mack <benni@typo3.org>