What is multi-arch x64+arm64 "Universal" Mac binary?

I think this might be involved with my GitHub Actions builds suddenly failing. I see this in the log:

2024-05-13T18:01:54.3884260Z --2024-05-13 18:01:54--  https://vcvrack.com/downloads/Rack-SDK-latest-mac-x64.zip
2024-05-13T18:01:54.4314050Z Resolving vcvrack.com (vcvrack.com)... 168.235.102.117
2024-05-13T18:01:54.5054460Z Connecting to vcvrack.com (vcvrack.com)|168.235.102.117|:443... connected.
2024-05-13T18:01:54.7383230Z HTTP request sent, awaiting response... 302 Found
2024-05-13T18:01:54.7387910Z Location: Rack-SDK-2.5.2-mac-x64.zip [following]
2024-05-13T18:01:54.7392640Z --2024-05-13 18:01:54--  https://vcvrack.com/downloads/Rack-SDK-2.5.2-mac-x64.zip
2024-05-13T18:01:54.7397220Z Reusing existing connection to vcvrack.com:443.
2024-05-13T18:01:54.9234330Z HTTP request sent, awaiting response... 404 Not Found
2024-05-13T18:01:54.9484220Z 2024-05-13 18:01:54 ERROR 404: Not Found.

Sure enough, when I go look at the VCV download folder, the only 2.5.2 SDK for Mac I see is:

Rack-SDK-2.5.2-mac-x64+arm64.zip

So instead of separate zip files for each platform, there is a single one. What is the best way for me to fix my GitHub Actions yml script to handle this case?

I didn’t see anything on the Automated building thread about this yet.