* Update license information. Since 7.4 upstream distributes source
files under dual license of Redis Source Available License
v2 (RSALv2) and Server Side Public License v1 (SSPLv1).
* Add entry to UPDATING.
ChangeLog: https://github.com/redis/redis/releases/tag/7.4.0
<ChangeLog>
UPGRADE URGENCY: LOW, however updating is encouraged if you have many instances
per server and you want to lower the CPU / energy usage.
* [BUGFIX] Replication: more strict error checking for master PING reply.
* [BUGFIX] redis-cli: use keepalive socket option for improved reliability.
* [BUGFIX] Allow AUTH while loading the DB in memory.
* [BUGFIX] Don't segfault on unbalanced quotes while parsing config file.
* [IMPROVED] serverCron() frequency is now a runtime parameter (was REDIS_HZ).
* [IMPROVED] Use a lot less CPU when idle, even with many configured DBs.
</ChangeLog>
