fix(UserConfig): cast getTypedValue() result to string in getValueBool()

PHP 8.4 made passing non-strings to strtolower() a fatal TypeError.
getTypedValue() can return a non-string under certain conditions, causing
the strtolower() call to throw. The (string) cast guards against this.

Fixes #59629

Signed-off-by: There Is No TIme <37583483+thereisnotime@users.noreply.github.com>

Author: thereisnotime

lib/private/Config/UserConfig.php

@@ -686,7 +686,7 @@ public function getValueBool(
 		bool $default = false,
 		bool $lazy = false,
 	): bool {
-		$b = strtolower($this->getTypedValue($userId, $app, $key, $default ? 'true' : 'false', $lazy, ValueType::BOOL));
+		$b = strtolower((string)$this->getTypedValue($userId, $app, $key, $default ? 'true' : 'false', $lazy, ValueType::BOOL));
 		return in_array($b, ['1', 'true', 'yes', 'on']);
 	}