Plugin reload fix (#7361) (#7362)

- call registry.check_reload when registering an event
- ensure that latest versions of plugins are loaded

(cherry picked from commit 5577a086c9)

Co-authored-by: Oliver <oliver.henry.walters@gmail.com>

src/backend/InvenTree/plugin/base/event/events.py

@@ -60,6 +60,9 @@ def register_event(event, *args, **kwargs):
 
     # Determine if there are any plugins which are interested in responding
     if settings.PLUGIN_TESTING or InvenTreeSetting.get_setting('ENABLE_PLUGINS_EVENTS'):
+        # Check if the plugin registry needs to be reloaded
+        registry.check_reload()
+
         with transaction.atomic():
             for slug, plugin in registry.plugins.items():
                 if not plugin.mixin_enabled('events'):