Change DOMCharacterData::appendData return type to true (#10690)

Author: othercorey

UPGRADING

@@ -73,6 +73,9 @@ PHP 8.3 UPGRADE NOTES
     See GH-9336
   . class_alias() now supports creating an alias of an internal class.
 
+- Dom:
+  . Changed DOMCharacterData::appendData() tentative return type to true.
+
 - MBString:
   . mb_strtolower, mb_strtotitle, and mb_convert_case implement conditional
     casing rules for the Greek letter sigma. For mb_convert_case, conditional

ext/dom/php_dom.stub.php

@@ -485,7 +485,7 @@ class DOMCharacterData extends DOMNode implements DOMChildNode
     public ?DOMElement $nextElementSibling;
 
     /** @tentative-return-type */
-    public function appendData(string $data): bool {}
+    public function appendData(string $data): true {}
 
     /** @return string|false */
     public function substringData(int $offset, int $count) {}