Enable TLS/HTTPS for legacy mailing lists

Subjects

• http://lists.typo3.org/
• http://lists.association.typo3.org/

Description

The security team keeps receiving reports on missing HTTPS termination for mentioned legacy mailing lists. Both services are excluded in our bug bounty program (see https://typo3.org/community/teams/security/bug-bounty-program) - however, it probably would be a simple change to avoid further similar reports.