Rack Mac download filenames changed in 2.6.x

the 2.5.0 version of the example plugin no longer works with Rack 2.6.x -- Rack used to distribute x86 and arm64 in a single zip - it's now split into two zips.

I've submitted a pull request to fix: https://github.com/qno/vcv-plugin-github-actions-example/pull/7