[DOCS] Fix BeforeRequestTokenProcessedEvent code example

The code example for the `BeforeRequestTokenProcessedEvent`
event listener implementation contains an error, since the
request token scope is checked for lower cased `loginType`
in `AbstractUserAuthentication`.

This change fixes the code example.

Resolves: #102899
Releases: main, 12.4
Change-Id: I5582b916b9399eb90672edf3f06a59d84e3bdef0
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/82613


Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: core-ci <typo3@b13.com>

typo3/sysext/core/Documentation/Changelog/12.0/Feature-97305-IntroduceCSRF-likeRequest-tokenHandling.rst

@@ -167,7 +167,7 @@ can be used to generate the token individually.
             // validate individual requirements/checks
             // ...
             $event->setRequestToken(
-                RequestToken::create('core/user-auth/' . $user->loginType)
+                RequestToken::create('core/user-auth/' . strtolower($user->loginType))
             );
         }
     }