wasm-opt is not used for linux aarch64

[dkristia]

🐛 Bug description

A linux aarch64 build for wasm-opt exists in the newest binaryen versions, but is not utilized here.

🤔 Expected Behavior

Wasm-opt for aarch64 should be used.

👟 Steps to reproduce

cargo install wasm-pack on an aarch64 linux device

🌍 Your environment

Include the relevant details of your environment.
wasm-pack version: not applicable
rustc version: not applicable