TYPO3 9.5 patch for #93764: slugs in non-normalized Unicode can produce incorrect urls

normalizer.diff

commit 0657788b1e5e0b5ea382083637438fc50c22baf8
Author: Dmitry Dulepov <ddulepov@snowflake.ch>
Date:   Wed Mar 17 13:47:07 2021 +0300

    [BUGFIX] Slugs in non-normalized Unicode can produce incorrect urls

diff --git a/typo3/sysext/core/Classes/DataHandling/SlugHelper.php b/typo3/sysext/core/Classes/DataHandling/SlugHelper.php
index dccc65af7f..fb4e8ca46e 100644
--- a/typo3/sysext/core/Classes/DataHandling/SlugHelper.php
+++ b/typo3/sysext/core/Classes/DataHandling/SlugHelper.php
@@ -108,6 +108,10 @@ class SlugHelper
         $fallbackCharacter = (string)($this->configuration['fallbackCharacter'] ?? '-');
         $slug = preg_replace('/[ \t\x{00A0}\-+_]+/u', $fallbackCharacter, $slug);
 
+        if (!\Normalizer::isNormalized($slug)) {
+            $slug = \Normalizer::normalize($slug);
+        }
+
         // Convert extended letters to ascii equivalents
         // The specCharsToASCII() converts "€" to "EUR"
         $slug = GeneralUtility::makeInstance(CharsetConverter::class)->specCharsToASCII('utf-8', $slug);