You have version 3.0.1 installed. Update to 3.0.2.
The beta should be bundled with the latest version. Currently 3.0.1 is bundled, while 3.0.2 has been out for a few days.
My site auto updates and I seem to always have to manually update Akismet, because it is overwritten and essentially downgraded. I'd like it if the current was bundled so this wouldn't happen.
I opened a ticket regarding this since it should be resolved before the final version.
But I'm opening this forum post as well given that the tracker has tickets still waiting review going back since June / July.