Note: I haven't personally tried that (and unfortunately I can't) but I'm pretty sure it will work. Complete any further config and you should be good to go. Edit your current WeatherSnoop devices, select WeatherSnoop in the Type popup and select the correct thing from the Model popup.
Download the new 3.0.0 version from GitHub by going to the repo and clicking on the Clone or Download button and clicking on the Download Zip button.However, if you want to migrate manually, here are the steps:
The rest of the process is going to be handled by the next Indigo installer (either 7.1.2 or 7.2 depending on a few mitigating circumstances). Boisy has the 3.0.0 version of the plugin up on GitHub, which was part of our migration strategy.