Author: Mark Nelson
MDL-66428 cachestore_redis: add Zstd compression support
http://git.moodle.org/gw?p=moodle.git;a=commit;h=de0b6d938cdfc4de2488f302bd7a7f71f0703c20
http://github.com/moodle/moodle/commit/de0b6d938cdfc4de2488f302bd7a7f71f0703c20
+ 3.8 en [compressor_php_zstd,cachestore_redis]