Redis caching issue with saving colour on Event Categories

When using Redis Cache and trying to change the colour of an already created category the new colour is not shown as expected because the “old” value is saved in the Redis Object Cache. To fix this we need to add wp_cache_flush() to the saving routine for the colour.

Adding this to events-manager/classes/em-taxonomy-admin.php line 172 inside the save function does clear the cache on save and let the user see that the colour option has been updated when saved, instead of having to way for the Redis Cache to be flushed before they can see the change.