fix bug in persistent.py

- use dirname instead of basename

Change-Id: Id563794a8e5f5c9e4d31750f089eb3b9c3150d94
Reviewed-on: https://forge.frm2.tum.de/review/c/sine2020/secop/playground/+/29353
Tested-by: Jenkins Automated Tests <pedersen+jenkins@frm2.tum.de>
Reviewed-by: Enrico Faulhaber <enrico.faulhaber@frm2.tum.de>
Reviewed-by: Markus Zolliker <markus.zolliker@psi.ch>

secop/persistent.py

@@ -129,7 +129,7 @@ class PersistentMixin(HasAccessibles):
                 if getattr(v, 'persistent', False)}
         if data != self.persistentData:
             self.persistentData = data
-            persistentdir = os.path.basename(self.persistentFile)
+            persistentdir = os.path.dirname(self.persistentFile)
             tmpfile = self.persistentFile + '.tmp'
             if not os.path.isdir(persistentdir):
                 os.makedirs(persistentdir, exist_ok=True)