Can't install binaries where releases don't include an architecture in the filename

[autarch]

The rustfmt releases have no architecture name in their filename - https://github.com/rust-lang/rustfmt/releases

[autarch]

I made a PR to add arch names to rustfmt release asset names - rust-lang/rustfmt#4679

If that's not accepted then I think the only way to support this is to find a way to check for the absence of an arch in the asset name, and then install solely based on OS matching and a prayer.

[autarch]

This has been fixed for rustfmt, but it'd be nice to not have to update each project to add arch names to their release filenames.

[autarch]

This was fixed in v0.0.29.