dev/joomla/#28 5.27 Upgrade fails

Failure is due to 'Undefined class constant 'POST_SELECT_QUERY'  see joomla#28

Civi/Api4/Event/Events.php

@@ -28,4 +28,10 @@ class Events {
    */
   const SCHEMA_MAP_BUILD = 'api.schema_map.build';
 
+  /**
+   * Add back POST_SELECT_QUERY const due to Joomla upgrade failure
+   * https://lab.civicrm.org/dev/joomla/-/issues/28#note_39487
+   */
+  const POST_SELECT_QUERY = 'api.select_query.post';
+
 }