Patch mail gem to handle TLS settings properly

While https://github.com/mikel/mail/pull/1526 made it possible
to disable STARTTLS with Ruby 3, there were a number of logic
errors that were fixed in https://github.com/mikel/mail/pull/1536.

We pull in those changes so that existing users don't have to
modify their configurations in strange ways to disable TLS.

Relates to https://gitlab.com/gitlab-org/gitlab/-/issues/399241

Changelog: fixed