add entry to UPGRADING

Author: jorgsowa

UPGRADING

@@ -23,6 +23,10 @@ PHP 8.6 UPGRADE NOTES
   . Invalid values now throw in Phar::mungServer() instead of being silently
     ignored.
 
+- Standard:
+  . Invalid mode values now throw in array_filter() instead of being silently
+    defaulted to 0.
+
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 2. New Features
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