fixed mailbox

Author: randolf-scholz

stdlib/mailbox.pyi

@@ -88,7 +88,7 @@ class Mailbox(Generic[_MessageT]):
     def __len__(self) -> int: ...
     def clear(self) -> None: ...
     @overload
-    def pop(self, key: str, default) -> _MessageT | None: ...
+    def pop(self, key: str) -> _MessageT | None: ...
     @overload
     def pop(self, key: str, default: _T) -> _MessageT | _T: ...
     def popitem(self) -> tuple[str, _MessageT]: ...