[Mailman-Developers] Small change to REST API for held subscription requests

[Aurelien Bompard]

> As for the `password` key: It's recognized by mailman.client and
> exposed within the mlist instance's `requests` property. But it's used
> nowhere in postorius and I would be surprised if it's used anywhere in
> hyperkitty (Aurélien...?). I guess it can go away.

No problem, I don't use pending mailing lists requests.

Aurélien.