fix incompatible type annotation with older python

Author: usrbinsam

CodeChallenge/models.py

@@ -331,7 +331,7 @@ def add_to_mailing_list(self, list_name: str):
  for addr in self._mail_recipients():
  mg_list_add(addr, list_name, self.mg_recipient_vars())
 
- def mg_member(self) -> list[dict]:
+ def mg_member(self):
  mg_vars = self.mg_recipient_vars()
 
  members = [