Univention Corporate Server 4.4 erratum 418 (security)

This update addresses the following issue:
* Django allows account takeover: A suitably crafted email address (that is
  equal to an existing user's email address after case transformation of
  Unicode characters) would allow an attacker to be sent a password reset
  token for the matched user account. One mitigation in the new releases is
  to send password reset tokens only to the registered user email address.
  (CVE-2019-19844)