Update humanmade/wp-redis with new caching functions

[Some new cache functions](https://make.wordpress.org/core/2022/04/29/caching-improvements-in-wordpress-6-0/) were introduced in WordPress 6.0:

* https://core.trac.wordpress.org/ticket/54574
* https://core.trac.wordpress.org/ticket/55080

The `wp_cache_flush_runtime()` in particular is quite interesting since it may be adopted by third-party plugins and libraries and expect to free up some memory, though the fallback/compat implementation does not free anything, so could result in exhausted memory errors. Since we have no way to determine whether runtime flushing is available, the work around that right now is to explicitly `wp_suspend_cache_addition()` for long-running (or high memory consumption) tasks, which is not ideal.

A `wp_cache_flush_group()` stub has also been introduced in 6.1, which should also be implemented.

The two upstream projects https://github.com/pantheon-systems/wp-redis and https://github.com/alleyinteractive/wp-redis haven't seen much activity lately, although there is [a ticket](https://github.com/pantheon-systems/wp-redis/issues/346) open for some of these cache improvements.

### Acceptance criteria
- [ ] The `wp_cache_*_multiple()` functions are implemented in our object cache fork
- [ ] The `wp_cache_flush_group()` function is implemented
- [ ] The `wp_cache_supports()` function is implemented (WordPress 6.1: https://core.trac.wordpress.org/changeset/54448)
- [ ] Tests for new functions are added, all tests are passing