feat: finish up UpdateAdapter (apache#177)

Signed-off-by: ffyuanda <46557895+ffyuanda@users.noreply.github.com>

Author: ffyuanda

casbin/persist/adapters/__init__.py

@@ -1,2 +1,3 @@
 from .file_adapter import FileAdapter
 from .adapter_filtered import FilteredAdapter
+from .update_adapter import UpdateAdapter

casbin/persist/adapters/update_adapter.py

@@ -7,3 +7,9 @@ def update_policy(self, sec, ptype, old_rule, new_policy):
         This is part of the Auto-Save feature.
         """
         pass
+
+    def update_policies(self, sec, ptype, old_rules, new_rules):
+        """
+        UpdatePolicies updates some policy rules to storage, like db, redis.
+        """
+        pass