Need to support architectures other than amd64 - use arch command in a get_arch function here.

[elijah]

asdf-ytt/bin/install

Line 48 in 71a4505

echo "${platform,,}-amd64"

If I need to install this plugin on a modern m1+ macbook - i can't.

Should stop hardcoding the arch here. Leaving myself an issue so I can help fix this.

The match should be against e.g. ytt-darwin-arm64