Fix exeption: module 'tempest.exceptions' has no attribute 'NotFound'

Related-prod: PRODX-27937
Change-Id: Id504e77ca84dfd861b4178cd5280689e1a85ad24
diff --git a/barbican_tempest_plugin/tests/scenario/manager.py b/barbican_tempest_plugin/tests/scenario/manager.py
index a1db4e6..d6d0e87 100644
--- a/barbican_tempest_plugin/tests/scenario/manager.py
+++ b/barbican_tempest_plugin/tests/scenario/manager.py
@@ -303,7 +303,7 @@
             available_stores = []
             try:
                 available_stores = self.image_client.info_stores()['stores']
-            except exceptions.NotFound:
+            except lib_exc.NotFound:
                 pass
             available_import_methods = self.image_client.info_import()[
                 'import-methods']['value']