Support linux/arm64

[georgealton]

Hi,
I've recently changed workflow, and now run ashai fedora remix distribution on apple silicon. Would love to run rain, and I've been building locally to keep working with rain.

Would you accept a PR that adds 'linux/arm64' as platform?

rain/.github/workflows/build.sh

Line 5 in b5685eb

declare -a platforms=(linux/amd64 linux/386 linux/arm darwin/amd64 darwin/arm64 windows/amd64 windows/386)

Thanks!

[ericzbeard]

Yes please!