`i386` platform is not supported

[filmil]

Is there a reason not to support it?

This seems to suggest that only x86_64 and arm64 are supported: https://github.com/bazel-contrib/rules_multitool/blob/main/multitool/private/lockfile.bzl#L41

[markelliot]

There was no particular rationale for its omission other than that when the toolset was originally built it wasn't an architecture we worked with/on, and not a common architecture for the kinds of tools we were depending on. Happy to take a contribution, shouldn't be too much churn to support