Updated openstack/openstack
Project: openstack/neutron  e768ee417368c46378009f54e5a9462ece50c3ec
null
Fix incorrect usage of sa.String() type

In downgrade of 4eca4a84f08a_remove_ml2_cisco_cred_db migartion
there is a mistake in usage SQLAlchemy String type.
Used sa.string() instead of sa.String()

Change-Id: I521dd63ca2b48e902ca2cb17c45a3fe996b060e7
Closes-bug: #1312124