Updated dovecot packages fix security vulnerabilities

It was discovered that Dovecot incorrectly handled certain imap hibernation commands. A remote authenticated attacker could possibly use this issue to access other users’ email (CVE-2020-24386). Innokentii Sennovskiy discovered that Dovecot incorrectly handled MIME parsing. A remote attacker could possibly use this issue to cause Dovecot to crash, resulting in a denial of service (CVE-2020-25275). The dovecot package has been updated to version 2.3.13, fixing these issues and other bugs. See the upstream release announcement for details.