Replaced e.message with str(e)

For logging the exception message: e.message has been
deprecated. The preferred way is to call str(e).

Change-Id: If14adfb9eae5fcd95822b07cea3bd66d16dacea2

vitrage/datasources/services.py

@@ -120,5 +120,5 @@ class ChangesService(DatasourceService):
                 for entity in datasource.get_changes(DatasourceAction.UPDATE):
                     self.send_to_queue(entity)
             except Exception as e:
-                LOG.error("Get changes Failed - %s", e.message)
+                LOG.error("Get changes Failed - %s", str(e))
         LOG.debug("end get changes")

vitrage_tempest_tests/tests/api/topology/test_topology.py

@@ -303,7 +303,7 @@ class TestTopology(BaseTopologyTest):
         except ClientException as e:
             self.assertEqual(403, e.code)
             self.assertEqual(
-                e.message,
+                str(e),
                 "Graph-type 'graph' requires a 'root' with 'depth'")
         finally:
             self._rollback_to_default()