[plugins] Fix scheduler accessing database while unbound from session

Signed-off-by: Ferdinand Thiessen <rpm@fthiessen.de>

flaschengeist/plugins/scheduler.py

@@ -60,6 +60,9 @@ class SchedulerPlugin(Plugin):
             self.blueprint.add_url_rule("/cron", view_func=__view_func)
 
     def run_tasks(self):
+        from ..database import db
+        self = db.session.merge(self)
+
         changed = False
         now = datetime.now()
         status = self.get_setting("status", default=dict())