Fix stub for zend_terminate_string()

Author: nikic

ext/zend_test/test.stub.php

@@ -20,7 +20,7 @@ function zend_test_deprecated(): void {}
 
 function zend_create_unterminated_string(string $str): string {}
 
-function zend_terminate_string(string &$str): string {}
+function zend_terminate_string(string &$str): void {}
 
 /** @param mixed $variable */
 function zend_leak_variable($variable): void {}

ext/zend_test/test_arginfo.h

@@ -15,7 +15,7 @@ ZEND_BEGIN_ARG_WITH_RETURN_TYPE_INFO_EX(arginfo_zend_create_unterminated_string,
 	ZEND_ARG_TYPE_INFO(0, str, IS_STRING, 0)
 ZEND_END_ARG_INFO()
 
-ZEND_BEGIN_ARG_WITH_RETURN_TYPE_INFO_EX(arginfo_zend_terminate_string, 0, 1, IS_STRING, 0)
+ZEND_BEGIN_ARG_WITH_RETURN_TYPE_INFO_EX(arginfo_zend_terminate_string, 0, 1, IS_VOID, 0)
 	ZEND_ARG_TYPE_INFO(1, str, IS_STRING, 0)
 ZEND_END_ARG_INFO()