Fix mc_project_version_update() return value

The function's return type does not match the WSDL definition.

This is a regression introduced by a80f447
which changed version_update()'s return type from true (bool) to void
Since mc_project_version_update() actually returned that, it causes a
side effect because void == NULL == false.

To avoid an unnecessary and potentially breaking change in the WSDL, the
function now returns true.

Fixes #25470

api/soap/mc_project_api.php

@@ -553,7 +553,8 @@ function mc_project_version_update( $p_username, $p_password, $p_version_id, std
 	$t_version_data->date_order = $t_date_order;
 	$t_version_data->obsolete = $t_obsolete;
 
-	return version_update( $t_version_data );
+	version_update( $t_version_data );
+	return true;
 }
 
 /**