Bump greenmail dependency

[swalchemist]

What version of UAA are you running?

76.29.0

What did you do?

UAA's dependabot.yml file blocks dependabot from upgrading com.icegreen:greenmail to version 2: Version 2+ was causing test flakiness, wait for it to stabilize. See https://github.com/cloudfoundry/uaa/pull/2314. When I tried version 2.0.1, the verifyThatBadUserAndBadPasswordCantSendMessages test failed, probably more because of breaking changes in the library than flakiness. We should try to get this test passing and see if any flakiness is still there in the library.

SmtpConfigurationTest > WithValidUsernameAndPassword > verifyThatBadUserAndBadPasswordCantSendMessages() FAILED
    java.lang.NoClassDefFoundError: jakarta/mail/MessagingException
        at org.cloudfoundry.identity.uaa.mail.SmtpConfigurationTest.setUp(SmtpConfigurationTest.java:34)

[cf-gitbot]

We have created an issue in Pivotal Tracker to manage this:

https://www.pivotaltracker.com/story/show/186814417

The labels on this github issue will be updated when the story is started.