ANN: Clojars one-off deploy tokens; emails on deployment

[Toby Crawley]

Howdy friends!

We recently made some improvements to Clojars relating to deployment and security. If you don't ever deploy projects to https://clojars.org, you can stop reading here.

## Single-use deploy tokens

You can now create a deploy token that can only be used to deploy a single version.

## Expiring deploy tokens

You can now set an expiration time for a deploy token. It can be set to expire in: 1 hour, 1 day, 1 week, 30 days, 90 days, or never.

## Receive an email when a deploy happens in any group you are a part of

You can optionally receive an email whenever a deploy occurs to any group you are a part of. You can control this at https://clojars.org/notification-preferences when logged in (also accessible via the settings navigation bar at the top of the page - you may need to do a hard refresh to get the latest CSS for it to render properly).

This feature is ON by default for new user signups, and OFF by default for existing users.

Please open an issue at https://github.com/clojars/clojars-web/issues if you have any questions or concerns.

This work is part of ongoing maintenance & security improvements sponsored by Clojurists Together (https://www.clojuriststogether.org/).

- Toby