[BUGFIX] PHP warning due to missing preg_quote

Fixing a missing preg_quote() call in ExtensionManagementUtility,
which causes a PHP warning and a failing preg_match().

Resolves: #55662
Releases: 6.2
Change-Id: Iaf1e21546741ae282016f433bf83f7e5663e3c7b
Reviewed-on: https://review.typo3.org/29145
Reviewed-by: Markus Klein
Tested-by: Markus Klein
Reviewed-by: Pascal Dürsteler
Tested-by: Pascal Dürsteler
Reviewed-by: Stefan Neufeind
Tested-by: Stefan Neufeind