fix: add newline at end of file (resolve black format error)

Author: pualcmd

casbin/management_enforcer.py

@@ -346,4 +346,4 @@ def add_function(self, name, func):
         self.fm.add_function(name, func)
 
     def self_add_policies_ex(self, sec, ptype, rules):
-        return self._add_policies_without_notify(sec, ptype, rules, True)
+        return self._add_policies_without_notify(sec, ptype, rules, True)