Amazon’s two-year-old Echo Dot and Echo Dot with Clock are both getting upgrades this year, with the new Echo Dot set for a major audio boost while the Echo Dot with Clock is adding a higher-density display. Even better, fourth-gen or better Echo devices are about to become Eero Wi-Fi extenders, Amazon said, while the Echo Studio is slated to a software update that improves the speaker’s spatial audio technology. Fifth-gen Echo Dot and Echo Dot with ClockThe latest Echo Dot comes with the same external design as the previous-gen Dot, but Amazon says it redesigned the interior to accommodate a …