Fix building of mailcatcher docker image for Ruby 2.7

Bumps [puma](https://github.com/puma/puma) from 5.6.7 to 5.6.8.
- [Release notes](https://github.com/puma/puma/releases)
- [Changelog](https://github.com/puma/puma/blob/master/History.md)
- [Commits](puma/puma@v5.6.7...v5.6.8)

---
updated-dependencies:
- dependency-name: puma
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

…-5.6.8

Bump puma from 5.6.7 to 5.6.8

Sometimes a response is posted and the department then changes its mind.

* Track the number of emails sent
* Track when the emails have finished enqueuing

The Authlogic gem uses SecureRandom.urlsafe_base64 internally but we can use
the SecureRandom.base58 method to restrict it to alphanumeric characters.

Devise has better support for alternative authentication systems and things like 2FA.

Once migrated there will be no passwords to reset.