fix: no accounts no send msg

apps/notifications/backends/lark.py

@@ -17,6 +17,8 @@ class Lark(BackendBase):
     def send_msg(self, users, message, subject=None):
         accounts, __, __ = self.get_accounts(users)
         print('lark', message)
+        if not accounts:
+            return
         return self.client.send_text(accounts, message)